The only GTS design I like better than SkidRow's is Dirk's, but his is only for '97+ XJ's.
FWIW, this is what can happen with the stock GTS...
Friend's '99 XJ landed a pointy piece of granite. Stock skid got pushed into stock plastic gas tank. It got pushed in enough that it pinched off his fuel pickup, which makes for a dead XJ on the trail. After lots of winching we got it back to camp, pulled the skid, the tank popped back into shape, and it ran just fine after that. One of the first things I did after that trip was replace my stock GTS with one from SkidRow. The tank on my '95 is metal, so if something like that happened to me, it probably wouldn't have been such a straight forward fix.