I have a OR-Fab carrier with can mounts. I have had the carrier for 2 years and still haven't gotten around to buying cans for it. I am thinking just going to the non-can version because I like the carrier but would like to bring the spare in closer to the body.
It got me thinking overall and I was looking at different rotopax setups. There are some cool ideas out there but I was wondering how many people actually carry fuel and use it. I have been lucky enough that I have only had one time on the trail where I would have liked to have had fuel with me. I guess in that thinking one time without fuel is one time too many.
I carry only 2 gallons, inside in a rotopax container. I have never used it, even roaming around Utah/Arizona/Nevada etc. But I make a point to fill up frequently if I'm exploring somewhere unfamiliar.
Even if I never use it, I feel good having a couple gallons in case someone else needs it.
Ideally I'd like to carry 4 gallons or so outside, but that won't be until I get a rear bumper/tire carrier.
I have the same setup with jerry cans. I picked up a couple cans at Jeeptoberfest and have used them a couple times. I got this so I didn't have to carry fuel inside the jeep again. Like for the boat or lawnmower! Every once in a while I'll put some in when I go wheeling, one time I wished I would have had some with me, but haven't had to use it on the trail.
I have hit my spare a couple times, now I try to take it off and throw it in back when I pull my discos off. The angle is much better without the spare. I haven't thought much about the weight. My front is heavier with the winch and bumper than it is on the back so maybe it helps balance it out more? Who knows. Most of the time the jugs are empty anyway. I think I lost about 1/4" on the lift when I put all that on the Jeep
I carried two jerry cans on the back of my 87 Wrangler while driving down the Alaskan Highway one January years back. Though the road is maintained, using the "Milepost" magazine that provides all the services along the way did not say that many fuel stops were closed in the winter. Late one night, running on fumes my options ran out, and thankfully I had the ten gallons with me that got me to the next service opportunity.
I still use the fuel can rig to go get the mower fuel and keep it out of the back.
All depends upon where I am going - going with others - a thru trail or a dead end trail - If I am on a "dead end" trail when I get to the point that 1/2 of the fuel in the jeep OEM tank is gone - I turn around - the extra fuel - at least in my case - is not to go further but to serve as a reserve in case of an emergency. just because it was easy getting in does not mean it will necessarily be just as easy getting out. So in answer to your question I almost always carry extra fuel when I am going off road - how much depends upon my destination and who is or is not going with me.