We have used a 7' wide for many years: when we first bought an enclosed trailer, the 6' wide were really tight getting through the door and didn't allow for walking and maneuvering around the front end when in the trailer. The 7' wide would allow to move around the front end while loaded: nice for tie down and stowing gear.
You didn't ask, but... I preferred a tandem axle trailer. It didn't seem to add a lot of rolling resistance, therefore lesser effect on fuel mileage, but gave a smoother ride and pull. I preferred a lower profile for less wind resistance. Our last trailer was 6-1/2': ample room for 5'11" me in boots to stand up except when passing through the loading ramp door. We have had an Expedition v-nose 7x16, a Haulmark square-nose 8-1/2x18 (the monster), and an Aluma all-aluminum v-nose 7x16. The 7x16 would haul two F3 model Spyders load end-to-end, one with a trailer hitch, but space was tight. The Spyder itself is close to 9' in length, I would suggest a minimum of 14' length: the longer trailer will pull straighter, the pull vehicle/trailer combo will fit into a typical park lot double length space, and you will have the extra room for gear.
Prices have changed/increased over the years, but my recommendation would be a low-profile, all-aluminum, 7' wide, tandem axle, v-nose trailer. Another member suggested the type of trailer with a liftable, fiberglass clamshell (??Ironhorse) that would be interesting to view: would have just about everything except copious cargo space.
Just my thoughts.