idk back spacing on the pro comps. you might need spacers, might not, but they'll keep the tires from rubbing on the CA's.
As for trim...some people sit at 3" on 31's and need 0 trim, I'm about 3-3.25 and had to trim in the front (took off the bumper, screw it). Throw them on and see.
His:00 TJ "Fiona" stuff/stuff/stuff
95 ZJ 3.5" w/242 swap-Sold
Hers: 15 JK Sahara-3" Teraflex