Good luck with the design. THe only way to know if something will hold up is to build it, wheel it, and hopefully not break it; if so just take that lesson and improve on your previous design. I have had a front skid (it goes just beyond the steering rack) in my garage for quite some time but really need to start thinking on mounting options before this wheeling season. I need to upgrade the front coils to 881's before doing so due to the weight increase. My 880's would not take the additional weight.
This is what I have for both the gas tank and the transfer case. THe gas tank skid weights around 30 lbs and I'm guessing the transfer case skid weighs just a shade under.