I'm on a run
So here's more of my opinions.
Item #1.
I wouldn't sweat the roof penetration issue. Stock, mine has 4 already, 3 of them quite large. A dinky feed-through for a roof top solar fitting can be installed and be easily waterproof for life. If you use 3M 5200 sealant, it's lifetime installed as that is one used in marine applications and is very tenacious and long lived. I don't have roof top solar, thought about it, but 200W of portable works well enough.
Item 8.
Because of the 4 trailer wheels, an E19 is less susceptible to sway. Loading and balance need to be considered. A WDH is highly recommended by me. I've towed with and without, and it greatly reduces porpoising when going over bumps and it transfers weight & stress. I tow with a 1 ton capacity, full size, 6L, V-8 van. Little issue with that vehicle of the tail wagging the dog, but I have felt some with high winds.
The WDH is a tired, beaten into the ground issue. Those who don't have one and swear all is great simply have never used one. They're a bit of an effort to use, but having fun is a lot of work, in my experience. I'd very highly recommend a WDH, and I have no preferences on brand or type.
Item??
Don't be afraid to get an older Escape rig. These fiberglass trailers last a long, long time. Any Escape, any vintage, is a pretty safe bet. It's the shell and the "bones" or structure that matter. All the do-dads, converters, microwaves, brakes, fans, etc. are common replacement items. Certainly, it's operating condition is important, but the appliances are just that..replaceable. You will need sturdy "bones".
Have fun.