Actually.. I don't have any "plans".. don't really need any. It's pretty simple actually.. here is how I build a bumper nowadays..
CNC Plasma Cut the Bumper Blanks (58" long).
Mark inward 1.25" from passenger side tapered end.. scribe X for spindle hole.
Use square to mark around bumper to other side for spindle hole.
Drill spindle hole with 1.5" hole saw.. both top/bottom of bumper.
Tack chain plate to 6" receiver tube.
Slide receiver in bumper till it bottoms on the chain plate.. tack and weld.
Drop clevis mounts in holes.. tack and weld.
Drop a piece of 3/16"x 1.88" x 8.25" flat stock onto the driver's end of bumper and weld it in place.. beating around the end with a 3lb mini-sledge.
Set bumper aside.
Grab 2x3 tube... 41" long. Mark/grind arc in end to match 2.75 pivot tube.
Grab 45deg latch mount (CNC cut on plasma table).. tack/weld to other end of arm.
Pound spindle thru bumper (rubber mallet).
Drop scrap piece of 2.75"x.500" wall DOM over spindle.
Slide 41" arm up to that 2.75" tube and mark centerline of receiver hitch on that 41" swingarm.
Tack piece of 2"x2"x1/8"x 16" long square tube (it's the vertical tube) to 41" arm.. centered on that mark.
Tack 2 pieces of 2"x2"x1/8"x 21" long square tubes (with 45deg ends) as the diagonals on the arm.
Fully weld those square tubes to arm.
Assemble pivot tube with mock up bearings.. pound the pivot's shank thru bumper.
Set arm on 3/8" thick spacers and butt it up to pivot tube. Tack arm to tube. Clamp down latch end of arm and run top bead between arm and pivot tube.
Squat down, stick welder inside bumper and tack spindle in place.. inside the bumper.
Disassemble pivot tube and remove arm (set arm aside).
Weld around spindle where it enters the bumper (top side).
Stand bumper up against the table and weld spindle inside the bumper.
Lay bumper back on table with bottom side up and weld bottom of spindle.
Lay another 3/16" end cap in place on passenger end of bumper and weld/hammer it in place.
Pass bumper to son so he can grind the ends down smooth.
Finish welding pivot tube to swingarm.. then set arm aside.
Grab 2ea 1/2" thick bumper mounting plates (CNC cut on plasma table) and 2ea 3"x3"x3/16"x 2" long square tube spacers and weld spacers to mounting plates (centered)... set aside.
Pick up piece of YJ/TJ rear frame/crossmember and set it on welding table.. set the bumper mounts in place on bolt holes in crossmember.
Go get a bottle of water and drink it while son finishes grinding bumper ends.
Son places bumper centered on the mounts.
Double check that everything is centered and then tack the bumper mounts to the bumper.
Remove bumper, flip it over and weld mounts solidly in place.
Reattach swingarm to bumper with mock up bearings.
Screw "Pull Pin" into "Pull Pin Barrel".. and grab one "J-Lock" (CNC Cut).
Open swingarm to "far enough" position and tack J-Lock in place on bumper (using assembled pull pin to sort of eyeball the location).
Tack Pull Pin onto swingarm where the arm meets the pivot tube.
Swing the arm open/closed a few times to check fit of "J-Lock" assembly. Weld "J-Lock" in place (remove pull knob so plastic knob doesn't melt).
Attach Mock Up Latch to other end of swingarm.
Grab a piece of 2"x2"x1/8" x 3" tall square tube (make sure son has welded and smoothed a cap on it).
Clamp that 3" tall tube to the end of the swingarm.. so it's flush with the end of the 45deg latch plate (the one welded to the arm's end).
Hold up the "hook" for the latch.. sort of hold it all together and tack the hook in place on the 3" tall tube.
Remove the 3" tall tube and fully weld latches hook in place.
Reinstall 3" tall tube, mock up latch.. and tack the 3" tall tube in place.. ensuring swingarm is flush with face of bumper.
Open swingarm and fully weld the 3" tube in place.
Grab a 1/4" x 2" latch "Tongue" (CNC cut on plasma table) off the shelf and slide it under the end of the swingarm.
Tighten latch "Ubolt" until it pulls the arm down enough to clamp that "tongue" in place.. tack tongue in place.
Unlatch and open swingarm. Fully weld "tongue in place".
Beat end of tongue downward slightly to give it a ramped profile.
Completely disassemble arm and set all components aside.
Reinstall bumper on frame/crossmember (ensuring it's centered).
Hold the lower mounting tabs (CNC cut on plasma table and prebent by son) in place under frame and tack them to bumper.
Remove bumper and finish welding the lower mounting tabs fully.
Hand bumper to son for cleanup.
Grab 2" receiver from shelf.
Drill 1/2" hole in top of receiver for "cinch nut". Eyeball it to make sure it's close to center.
Insert a bolt into the 1/2" cinch nut and drop onto the hole (bolt will center it over hole). Tack nut in place and remove bolt quickly.. before heat siezes bolt inside nut.
Weld cinch nut fully.
Stand swingarm up on welding.
Set receiver tube ontop of swingarm vertical tube and eyeball it to get it centered. Tack it in one corner only.
Lay swingarm down flat and lay a square on the arm. Eyeball the "reveal" between the vertical edge of the square and the now vertical receiver tube and tap the tube left/right to make it square up with the main swingarm. Tack receiver in 2 more places to keep it from moving.
Weld receiver to verical tube.
Grab a 2" triangle gusset (CNC cut on the plasma table) and hold it in place under receiver tube.. tack it in place and weld it in.
Give swingarm to son for cleanup.
Grab 3/8" thick tire plate (CNC cut on plasma table) off shelf.
Grab predrilled (son again..) 2"x2"x1/8"x10" long tire mount tube off shelf.
Drop three 1/2"-20x1.5" Grade 8 bolts into the 3 lug holes in tire plate. Weld the bolt heads in place.
Drop that predrilled tube onto the tire plate.. and slide it up against the lone lug bolt.. tack the predrilled tube in place. Double check the tube to make sure it's square with plate and then burn it in. Add 2" gusset between tireplate and tube.
Give tire mount to son for cleanup and tell him to go make the hardware box up.. and prep everything for shipping.
Note: Make sure to do all this within 4hrs or else your not gonna make wages or shop rent for the day... seriously.