Disclaimer: I haven't read all 8 pages of this thread...
* Scepter makes CARB compliant cans and many (including me) believe CARB compliant gas cans are another sign that our country is spiraling downward (for some reasons some states think California knows what it's doing and they copy our state's **************** laws)
* When most talk about Scepter gas cans they're referring to the military style cans (olive drab color)
* Sceptre military cans can be purchased used and there are two "different" containers, those used for gas and those used for diesel. The difference is the gasket and they have different colors (I think red is gas and yellow is diesel but I could have that backasswards). The gasoline cans use Viton (material) gaskets. But you can buy the diesel containers and buy Viton gaskets (there was at least one guy selling them as I bought several from him).
* I've read that since it's illegal to use non-CARB compliant gas containers, law enforcement will/have pulled folks over and written them up (here in Taxifornia). I searched for that and didn't find it easily but I know I've read that before.
All that said, I have Scepter cans and like them a lot. I bought them used at a decent price and bought the Viton gaskets too.
I also have a JKUR and I will not carry gas in any container inside my Jeep. The smell can be overpowering but I fear the worst which is gasoline inside the vehicle in an accident, etc. I'm waiting to have the funds to buy a new rear bumper with swing away spare carrier that I can add a gas can carrier to it.
If I HAD to carry fuel (I've been lucky enough to either not need it or have friends with pickups, etc. who will give me gas that I pay for) I would consider strapping a Sceptre gas can (or even a smaller 2.5 gallon gas can) to the factory spare tire's wheel. I think that would be a real option.
Links:
Some info on Sceptre gas cans and other related info:
https://www.survivalmonkey.com/threads/portable-fuel-storage-jerry-can-faq.49574/
There are at least 17 threads that address Sceptre gas cans and other options on Expedition Portal. You can search for them if this link doesn't work:
http://www.expeditionportal.com/forum/search.php?searchid=1492600
I was looking for the post/thread for the guy selling Viton gaskets but can't find it right now.