I had ours built about 5 years ago and I've been very happy with it. It's withstood some very strong wind gusts (up to 80 mph) and sustained winds during storms here in Oklahoma. There are 8 hurricane anchors plus 20 rebar steaks to hold it in place.
It's 18' wide x 41' long x 12' sidewalls.....approx. 15' in center. I added a 12' wide x 20' long lean to on the side for our pop up. You could park your tow vehicle there.
When I had it built we owned our LaCrosse tt, but it houses our new 2017 Crusader 5'er perfect. The trailer is listed at 12' 9" tall and it's wide enough to open slides on both sides.
I also had a 100 amp breaker box, with cut off, installed next to the meter on our house. Then they ran a line out to the RV port to an electrical box like you find at a campgrounds with 50 amp, 30 amp and 20 amp plugins.
I hope this helps you.