Have you ever put any kind of trailer in that driveway?
The last thing I would worry about with those trailers is the rear drag.
Looks like the length of both trailers is going to cause problems using the garage for other cars while it is there.
It looks like you will have to unhook the truck and park elsewhere or leave the front of the truck in the street.
Mailboxes on both sides of the driveway (and across the street) and the width of the street looks like trouble to me.
If I had to do it I think I would go with the 5er just for the shorter overall length while hooked up.
Is there any way to have some sort of trail run or test drive to see if it works before buying? Maybe the dealer will bring one by and see if it will fit... You are the one holding the money they want so it does not hurt to ask first.