Nice to see you are looking ahead to all the money you can spend????
If weight is not a problem, I would go with the Trojan T105 6V deep cycle and pair them up for 12V
to satisfy the house demand. I run 4 of these in the Clipper, but they are heavy!
If you are running close to max weight you are probably better with a single 12V deep cycle for the house batteries.
An auto/truck battery will not stand up to repeat deep discharges and will cost you more in the long run.
The deep cycle are not really suitable for a starting battery, so again better buying whatever the chassis OEM recommends for your unit.
I have modified/installed a SurePower 1315-200 battery seperator for the Clipper #137 and it works great. Allows charging both ways, (as I have lots of solar power).
Good luck on your Airstream travels.