Charging a battery from a charger in my tow vehicle

Thanks.  I'll take a look at that generator.

Lets say you used 50 amps from your batteries, at 8 amps (50 /8 amp hours) it's gonna take 6.5 hours to recharge your batteries...do you really want your tow vehicle to idle that long?
I would go for the generator, gonna be cheaper than wearing your tow vehicle out.

I have a pair of 2000 Hondas, and yes they are pretty quiet. I didn't think you wanted to spend a lot for one time use, so I suggested the cheap one. If you are in a campground, you need to know what the generator policy is because they may not allow use or have limiting hours. People will complain no matter how quiet your unit is if you are not obeying the rules.

Since you said dry camping, I thought you might be in a primitive area instead of a campground. If there is electric nearby, perhaps you could have two batteries and carry one to a place where it can be charged and rotate them as needed.

The 12 volt DC out on Honda generators is not regulated and will do a poor job of charging. The charger in the trailer will do a good job provided that there is not too much voltage drop in the wiring between the converter and the battery. Now that is a very big IF, because few have wire heavy enough and there is too much distance. You can try it and see, IF the battery is not discharged very far you should see 13.6 volts at the battery. IF the battery is at or below 12 volts with nothing on, the converter should deliver 14.4 volts when plugged in, but the WFCO converters rarely go into high charge, partly because of inadequate wiring and partly because it is a cheap unit. So that leaves you with one better option and that is a high quality battery charger plugged into the generator.

Here is a good site for information: link The site is a bit dated and some of the voltage information is not exactly like your setup.