So are you planning to bolt through the frame? Personally, I wouldn't do it that way, but it's your perrogative. Newer Toyota frames are notoriously thin and if you don't sleeve the frame where you drill, you are going to collapse it when you really tighten the bolts down. Further, you also have to watch out for electrical wiring on the inside of the frame rail as well as fuel and brake lines when drilling. A flange type mount welded to the outside of the frame rail is a preferable attachment method....just make sure you fishmouth, make circular, or rotate a square into a diamond, any plate being welded to the frame so you don't introduce a stress riser to your frame at the weld point.
As for just buying the premade ones....I disagree with the others comments. You're already using TWICE the thickness of material of the Trail Gear ones if you go to 1/4" wall tubing (a good thing). Personally, a good 3/16" thick walled DOM in even a 1.75" OD would be sufficient and keep the weight down.
Remember when talking armor, that you're already driving a very heavy rig and adding weight to protect it is a necessity, but you want to go with as light as possible while still offering the protection you need. Simply put, the 1/8" wall tubing most sliders are made from is sufficient for mild use, but if you really push it, you need thicker tubing with LOTS of legs to the frame. I'd say 1 leg every 12-16" max.
I've seen a lot of 1/8" walled tubing dimple in from hard impacts. It will generally keep the rocks and the sliders out of the body, but they will eventually dimple enough to look like crap and when I build something, I only wanna do it once. With a heavier walled tube, the only maintenance will be repainting when you scratch the paint off.
BTW, Chris....happened to look at your adventurefilms website (don't really know why I was compelled to) but in any case....NICE work! Very beautiful and artistic pictures. I also like the fact that you have the strength to acknowledge your beliefs. Kudos to you and I wish you much success.