Routing/charge control for alternator charged house battery
looking for advice on locating a house battery, I'm converting a passenger E350. My electrical demands for the house system are going to be relatively low (exhaust fan, LED house lights and a few USB chargers for small electronics) and I'm gonna keep everything 12V DC, no inverter. I'm thinking that a single deep cycle house battery charged off the alternator with an isolating solenoid is the right solution for me, but I'm left with a few questions.
What's the best location for the battery in a system like this? I'm thinking not only of battery location for space usage but also for cable routing as I'll need to run large gauge wire for charging between the starter batt/house batt. Is it better to mount close to starting battery to minimize the large gauge cable run? Frame mount underneath or inside? What has worked well for you all?
Also, would I need a charge controler in this system? I am assuming there is some sort of a charge control system between the alternator and my starting battery right now, is this control sufficient to also charge the house battery? or am i gonna trash my hose battery in 6mo that way?