30 ft is plenty big for two people who like each others company. If you don't then 40ft will not be big enough.
A 1 ton truck is not to much for a 30ft trailer. It is carry capacity that you are concerned about in a 5er not pulling capacity. A 3/4 ton will pull it easy but you can get very close to the carry capacity of a 3/4 ton in some of the heavier 30ft trailer, especially if you add in spare fuel tank, generators, firewood, tools, etc into the bed of the truck. You will want to consider a auxiliary fuel tank or plan to carry 10 or so gallons in cans. You will not absolutely need extra fuel capacity, but it is good to have sometimes.
I think you are about right with your choices. I would suggest that you try to get a 5er with 16 inch wheels so you will have a larger choice of LT tires instead of ST tires.
You seem to be staying along the borders and low elevations which puts you into the hotter regions in summer. For the summer months, you will be happier with two AC's. That means 50 amp service.
If you are going to boonedock for very long, you may want a generator.
There is more I could add but others will cover other wants, needs, and desires of full time 5er owners.