What Dometic fridge do you have? The Westy Fridge uses ~7 amps and from experience will only run off a group 41 battery about 4 hours before the voltage drops enough to cause the fridge cooling to stop. 
The holes in the floor to let leaking propane out also requires holes up high for air to enter to  replace the propane. The regulator can also vent under some conditions. Both need to be outside the living space. 

Dennis

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Don Hanson
Sent: Saturday, July 4, 2015 11:33 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Batteries and solar panels!

   I have turned on my Dometic on 12v and it'll go about a day before it drains the small starter-sized battery.....but mine happens to work quite well on propane, which I have in a normal tank under the sink, with vent holes drilled through the floor (propane is heavier than air) in case it springs a leak...a 'regular' tank last me about 3 weeks.  I leave it on all the time when I am camping or traveling or at a bike race...Much easier to fill, you don't have to take the whole van to a hose...