Yup you can build your own, but also a slightly easier option for the LJ and in budget would be the Congo Cage. Its just a frame that goes from windshield to rear bumper, you have to buy a rack separately, but if you're mounting an RTT, you don't need the rack....just the frame.
The Congo Cage has one of the HIGHEST payloads both dynamically and static in the industry, for the lowest price. Also with a few "flips" of some pins, the congo cage flips out backwards allowing you access to your ST.
Check it out. You'll love it I'm sure! :sombrero: