Questions, space, towing, upgrades???

We just discovered TM on the web a few weeks ago. We went to look at them near Dallas (4 hrs one way) and really thought they are neat! We are debating on size. It is my husband and myself and two large retrievers that will be traveling together.

We are debating the 2720 SL and the 3124 KS. No question about the room in the 3124KS but our current vehichle is a Nissan Quest. What kind of tow vehicle do we need for the 3124KS?

Also, we live in Texas and we are also folks who like our creature comforts. what type of upgrades would we want? Anyone tried the electronic levelers? Waht about bigger water tanks?

ANY input would be nice!
Thanks so much!

Mimilove