I have a similar issue to you. I haven't posted because since my return to JF a few weeks ago I've already seen 100 DW posts and I know how frustrated the regulars get.
I don't have DW (I have had it) but I currently have that evil precursor where you just know it can become DW if you don't speed up/slow down. Same speed as you, right around 48mph. I've played with tire pressures and that only modulates the speed at which it occurs.
Mine clearly starts on driver side. When there is the initial precursor it is really only the left side. If not stopped it can propogate. I've moved tires all around with no change.
I had a local jeep shop check the front end, they said all was tight and ok, but when I got home and checked my t-bar was not torqued down to spec. I fixed that but no change.
Alignment alleviated the full blown DW, but the precursor oscillation is still there.
Something is out of balance and begins to oscillate noticably at ~48mph. DW occurs when that frequency matches the harmonic frequency of the front end (springs, bushings, bars etc.)
I'll be redoing the tire balance.
I'm due for a brake job anyway, so I'll put new discs in front, maybe one of those has enough runout that it causes the vibration (although I don't feel pulsing brakes)
I've got poly bushings in the mail for my trackbar
If above doesn't help I'll just start going through things. TREs (appear snug but who knows), knuckle/hub/bearings, pull the CA and check bushings etc.
Frustrating thing for me is this all appeared after a 2" lift and shock install. Everything is installed correctly. I don't know if I always had the oscillation and never noticed beacause the old setup was damping it or what...
Very frustrating but hang in there, you'll find it.
'03 Sport, Patriot Blue
'04 C5 Corvette