Nice idea, except why only 20 ft long, many pickups are longer then 20'.
Also with only 16' in width it will be a bit narrow for two full sized vehicles.
Location, Direction, Available Space
I have the space for the 40 ftr along the edge of property / treeline at the driveway, however because there is a public right-of-way turnaround on the property, I only have room for a 20 ft parallel sea can.
This available space is also why I'm thinking 16 ft wide is doable between the sea cans, 18 ft wide is preferred.
20 ft length should be fine for my needs, but I could put a 3-4 foot overhang (rain guard) at the front for some extra length (probably $30K cost)
my purpose is primarily for parking the '64 El Camino (17.5' L x 6 W'), and a second vehicle, or my BX tractor. My Silverado is shorter. and slightly wider than the El Camino. The space between the sea cans will also be a garage area, work space. If I can go to 18' that would be preferred though.
If I can get this set-up done, it will lessen my need for a 30 x 40 ft pole barn at the back end of the property. (probably $60K cost)