Sunshade fabric is cheap... maybe hit up one of your local custom manufacturers for a couple square years of the fabric, heck, even scrap fabric would work for a banana plant.
We have a mister set up out here (can be run during frost too) but so far the temps haven't been much over 105°.
Since the big shade trees got cut down last year I leave the "winter greenhouse" frame set up but with a 5' strip of scrap shade fabric across the top instead of the clear plastic.
More (inside) pics at:
Dwarf Orinoco not so "dwarf" any more?