I replied to your MUD post, but I'll copy/paste it here as well for the folks who can no longer stand IH8MUD because it's nothing but armchair mechanics who love to point out everything that you do is wrong or should be done better or should cost more.....
Chris.....I've had this issue for a long time. My canister is located under where the spare should go, but same concept. It was so bad at one point that vapor would pour from my gas cap so heavy it would turn back into liquid and run down the side. I carried wipes just to clean it on the trail.
I checked all hoses and replaced the gas cap last year. Still had the issue. For the past 12 months+ I never filled all the way up unless I absolutely had to. Especially not right before hitting the trail. I always thought the charcoal would not dry out, but since then I've had very little trouble with the vapor/smell. Not in the heat, not at altitude. I *think* the charcoal canister gets overwhelmed from all the fuel in a full tank sloshing around and expanding from the heat/altitude and that's where the smell/vapor comes from. By not filling all the way (or giving that last squeeze at the pump after the auto shutoff) I'm leaving some room for all that to happen and the system to cope with all the extra vapor.
I also looked into a cheap fix like the 80/Dodge canister, but I couldn't find anything. I had no issues this year at all. Whether that's luck or it really worked, I don't know. But I'll take it for now.
Also, I left my truck running for a few minutes at altitude prior to shutting it off to let the EVAP system catch up.. As soon as you shut down, the EVAP system stops working, although when at it's worst the vapor would still continue to purge at the gas cap. I would slowly open the cap and allow the pressure to release. I think if I were to just twist the cap off quickly, I'd get a face full of fuel, so go slow when you do that.
Surely, someone on MUD is gonna reply with a better way because they know more than I do. But, my free test/fix worked for me and I had no trouble this year on the trail. But again, everyone over there gets out more than I do too.....
I sent you a PM as well. Derek at Stevinson said they've never replaced a charcoal canister for a 100. That's what prompted me to look at what else might be wrong.