Rear Travel-what limits travel most, springs or shock mounts

I want as much travel as possible in the rear, and Jeepspeed guys all tell me to cut through the body and build shock mount hoops, tied into a cage.

Can anybody tell me what travel can we get using only bolt on parts?

And I guess the next logical point is how to cut into the body if I really have to. I'm more interested in travel to absorb 'hits' at speed, than flex for crawling

You really don't need to cut into the body unless you are doing Jeepspeed and need that type of stuff. You can get a good amount of travel with bolt on parts, what sort of things are you going to be doing that you need it the most? If you want the most travel, then get rid of the leaf springs, and then go to a long arm coil over system from some of the various companies, that will give you a lot more travel then shock mounts.

I'm trying to K.I.S.S. and still have a machine that can move down roads in Baja at speed. I think I'd be ok with good long leaf packs and good shackles. I've seen a few posts about using longer leaves, like S-10 Chevy's.

The most important thing from what I've learned is overall correct setup, e.g., limit straps, bumpstops, and correct spring rates and shock valving when it comes to front-rear bias, or you end up with a front end that's correct, and a rear that bounces up as it leaves a jump, causing you to come down HARD on the front.