FOAM! USE FOAM!! lol! 
never seen that corrugated plastic sheet before. i know they never had it in store when i worked there. Looks like it would be a nice light weight way to go about it. However, the black plastic could work really well because of its size. its 10 x 20? if tight enough it probably wouldn't sag to much. And you could roll it up for next year. the plastic sheets are nice but as you say storage and you would have to attach each one. i would try the black plastic first then if it doesn't work out roll it back up and use it for something else no harm no foul. that canopy top is nice to because its the same size all ready as long as it flattens out. and its black. I would recommend a black tarp but there hard to find in black at least they were last year. i had to get a dark green one for my walk in. it works because you cant tell its green at night. Ill keep my thinking cap on and see if it comes up with anything else.
never seen that corrugated plastic sheet before. i know they never had it in store when i worked there. Looks like it would be a nice light weight way to go about it. However, the black plastic could work really well because of its size. its 10 x 20? if tight enough it probably wouldn't sag to much. And you could roll it up for next year. the plastic sheets are nice but as you say storage and you would have to attach each one. i would try the black plastic first then if it doesn't work out roll it back up and use it for something else no harm no foul. that canopy top is nice to because its the same size all ready as long as it flattens out. and its black. I would recommend a black tarp but there hard to find in black at least they were last year. i had to get a dark green one for my walk in. it works because you cant tell its green at night. Ill keep my thinking cap on and see if it comes up with anything else.
