what size bat for van

If you can recharge daily,you may get by with a 100 amp deep cycle.
The firdge you have will play a big part.
Being able to run the fridge and recharge off the cars alternator will also make a difference.

I think standard Bushtrackers have three 130 ah Kyocera solar panels and two 100ah batteries, because they are usually in non powered camp areas.

For overnighters, I cannot see you needing more than two solar panels and one 100ah battery.

I am a bit obsessive - too much is never enough- I have 4 x 130 solar panels and 3 x 100 ah batteries !

Willie.

Zacc,
We have 2 x 100ahr batteries in our van. We freecamp quite a lot and use a generator 1-2 hours most days to keep the batteries topped up.
I would suggest that 1 x 100ahr battery would be adequate for your needs if you only need it for overnight stops (assuming a powered site each second or third night to fully recharge your battery).
Easiest way to work out how much power you need is to calculate your power usage.
Assuming you use gas for your fridge, then you only have lights and water pump, if you have one, both have minimal power requirements, and a TV - about 4-5amps per hour.
A 100ahr battery gives you 50ahrs of usable power (so as not to run your battery too far down and ruin it).
Estimated usage would then be - lights and water pump - about 10 ahrs - TV - about 15 ahrs = 2 overnight stops.

Hope this helps.

Jeff.