It's not necessarily at one stretch, it could also be for several days camping away from services. One of the places I've long wanted to go is about 100 miles

It's not necessarily at one stretch, it could also be for several days camping away from services. One of the places I've long wanted to go is about 100 miles from the nearest town with a gas station, but the roads are particularly rough so I don't expect to get highway mileage or anything close to it. In my past off-roading I've gotten roughly half my highway mileage, so let's say it costs 200 "miles worth of gas" to get there. If it takes 200 miles to get in, it also takes 200 miles to get back out, plus some margin for error, plus whatever I burn while I'm there. A few days of cooking and stuff can burn a few gallons, more if I'm also running the fridge, which is really nice on a long trip. Add that I might want to visit a few sites over a few days, and I could easily see needing more than my existing 500-miles-in-ideal-conditions range. It's trivial for me to carry another 10 gallons, which doubles my highway range to 1000 miles, and that's with one of the most fuel-efficient hatchbacks on the road. A larger vehicle would need quite a bit more. I simply don't know a way to do that with an EV. Now admittedly that's a contrived example, but it's a just-slightly-more-extreme version of some real trips I take from time to time, and it's a trip I do honestly plan to take one of these days.