A quick check you could do is look in the AC breaker panel for a breaker labelled something like "charger"...My '96 Mallard has a breaker in the panel for the battery charger, so it's listed there.
As for 120V without having AC hooked up, that's anybody's guess. I've never had a camping unit (TT or otherwise) that had an inverter built in, so my working theory is it's not a popular option.
TT: 2013 Zinger ZT33BH
TV: 1986 6.2 Diesel Chev 3/4 ton van