Riveting wont work. You want to cut out as much material as possible and tie the patch panels in to the uniframe. The XJ frames get tweaked easily as it is, let alone without that extra support.
Make friends with somebody that has a welder and learn. Mig welding is real simple to get the hang of.
1996 Jeep Cherokee- Project-- Rusty's 8in long arm, SYE kit, Teraflex driveshaft, Cragar soft 8's 15x10 with 33x12.5 Firestone Destination MT's, Eaton Tru Trac in the front