my 2017 teryx4 le has a full windshield and full hard roof, and rear window mesh/net and I tow with an open trailer only no issues.
* I don't think I would drive with it backwards on the trailer as it could create a parachute effect maybe I don't know. But I have it facing the front of the trailer and no issue. The window doesn't even appear to flex etc. It doesn't move when the teryx4 is at 55mph on its on wheels not sure how 65-75 would a whole lot different.
Orange 17 Teryx4 LE, 4.5k winch, Full windshield, Roof, quadboss front rack, full spare, custom diy dog platform for rear seat