Welcome to the forum! It would be no different than if the converter on my trailer died and I hooked up a smart or a stupid charger to the trailer battery. I do this all the time when I'm not camping. I have a small 2 amp charger that I hook up to the trailer battery so that I don't have to keep the shore power cord plugged in all the time.
Most chargers have alligator clamps that you simply clip onto the battery posts.
2006 23B Hybrid with 10k round bar WDH
2011 F150 4x4 SCREW Ecoboost, Max Tow, Integrated TBC, 3.73 LS axle, Firestone Ride Rite airbags.