Update time: 1st time using the covers it was very windy, and the left side cover actually blew off the tractor (do NOT try and transport on a trailer with these covers on!), so I emailed
@bird dogger to discuss, and before I could log back in he'd dreamt up a solution (additional tabs with magnets to be sewn along lower edge), made it, and shipped it to me, I was blown away! He also came up with an alternative, possibly superior solution, using a large paper binder clip to hold the lower edge tight (see pic).
I did not even try sewing the tabs on, but the binder clip worked perfectly! It was COLD this time out, and the tractor was able to idle up to 1 bar, and operated at 3 bars all night with no issues.
Solid product, with excellent support. Thanks again David!