If by "convert everything" you mean "convert the
12v electrical system to a 120v system" you really don't need to do that if all you want to do is eliminate the big wet-cell batteries. A modern converter-charger will provide you with stable DC power without having a battery in the loop if you wish, and you could buy one of the small AGM batteries designed to support breakaway switches for trailer that don't need a battery otherwise.
If you mean to convert your various propane appliances to 120v that's another issue, and you'd be better off adding 50A service to your trailer if that's your goal, since the demands for that could be pretty high for a 30A setup.