FWIW/IMHO? All of the clear plastics have a specific amount they can torque or bend, and they all have a certain amount of distortion that they can add to your field of view if you're looking through a bent piece. I'd think that if you went all 1-piece for the front wind screen, 1) it would take some serious doing to get it installed (read distorting the plastic to get it all in place), and 2) you'd probably end up with a big distortion bend right down the middle where the angle between the two windshield panels come together.
Not sure where you are geographically, but early season and late season in New England there are cool fog days/evenings when the only way to get better visibility is to unzip the front panels (smiles) and roll them up. If that's not an issue for you I'd totally close them entirely. But I think 2 separate panels will be WAY easer for installation and removal for cleaning/seasonal storage, as well as less running stress down the middle of a plastic panel.
Seriously, just guessing, just my two cents after installing and removing my enclosure a couple of times.
Bob.