If you're buying new, you can do what I did. Instead of the battery tray they mounted 2 grp 31 AGM batteries under the sink next to the FW tank. One thing I liked about that option is keeping the batteries in the heated area of the camper to give better battery performance in colder weather.
Go to about the 7 minute mark in this youtube
youtube Laredo tourOn the down side, it does mean a smaller FW tank...
For that matter, if there's any other custom mods you might want, don't hesitate to ask. Rex built my Adventurer with dual propane tanks even though a single tank is standard.