Thanks for the info. The idea I am working with is a Uhaul17 ft box truck living in the front 8ft. The slide up door will be replaced, with a door that opens like a tailgate that will become the floor of a greenhouse. Then the roof and back wall will fold out, then the right and left sides of a greenhouse. In the back 6 feet of the truck there will be 4 or 5 rows of vertical towers hanging from side to side, hanging on garage door tracks. That will extend out over the tailgate(floor) into the greenhouse and then retract back into the truck when the door is closed. I am hoping to get 5 hanging towers in each row, with 4 rows and each 5ft tower having a head of lettuce every 6 inches, along the length, hopefully 10 plants. With 4 sides on the PVC post, 40 plants per tower, 5 towers in a row and with 4 rows. My plan is 40 * 5 * 4 = 800 plants at $2.00 a head every 4 weeks or do 5 rows with every other row at a different planting date, to get 2 crops harvested. 3 rows then 2 weeks later 2 rows. for a total of 1000 heads.