If I didn't want to do any upgrades or changing but wanted to get underway for camping for a two week trip, I'd get a second battery and hook it up to the RV battery with jumper cables.
A guy might be a little forward-looking and get a bigger battery for the future or the same size if the existing battery is new and of good quality. The latter choice would allow the use of two similar batteries paralleled for permanent connection.
BTW, get a hand-held multimeter. $10 will save a $75 battery and eliminate any guessing as to the condition of the battery.