If you can, get non-ethanol gas for small engines. Can't tell you how many carbs and fuel lines that have gone bad before I stopped using the 10% ethanol in them.
We use one of the DR lawn vacs towed by a 21hp lawn tractor. It does well as far as picking up the grass and leaves as long as you don't let the grass get too high between cuttings or mow when it's wet. Even then, if you're careful to mow in a counter clockwise circle to keep the vacuum hose...
It might block a little of the UV light, but overall, will probably keep the inside temp warmer than if the plants were uncovered. BTW, they work great for keeping deer out of sweet potatoes!
I've got one of those 4-cycle Troy-bilts, so that's good to know. I only have the attachment with the three plastic cutter heads, which doesn't do as well for cutting grass, so a couple months ago I bought one of the Shakespeare Easy wind Bump & Go heads. Using .105" Ugly Line in it for now...