In the past we built a bus and had a catalytic heater which is nice as they don't require electricity to work. Great for boondocking. With this small of unit, we figure a couple candles and terra cotta plant pots will heat up nicely. There definitely is not room for a catalytic heater. As far as the model goes, I am not sure. It has the couch as well as the dinette. Super clean rig, less than 43k on the unit and was owned by a familty that kept it garaged and they maintained it well. It has been restriped too.
I did take measurements also. Just don't want to spend $180 on upgrading to this larger tank if it won't fit. We won't use the heater, Just the stove and fridge on propane. Also adding a solar panel, AGM coach batteries and switching lights to LEDS.