For mud you prolly want to go as big as you can. IFS will handle 35's fine, especially if you're not doing any hardcore crawling. You may have to crank the torsion bars a little and put some shackles or add-a-leaves in the back, but the 35's should fit pretty well. I little fender trimming/pounding may be in order too, but that you can do when the time comes.

Another thing, some people may tell you that 35's are too tall for 4.88 gears. I'm running 33's and 4.88's and I almost wish I had bigger tires. My engine screams at 80 on the interstate with the 4.88's, I think 34's or 35's would give me perfect gearing. All just a matter of taste I guess.