As the gent ahead of me said. Add a front flap, but, do not get it too close to the ground or it will kick every firkin thing in the road up and most of it will hit the tire face.
This picture is with the front wheel setting in a wheel chock and it is about 3 1/2" more in the air that when not on the trailer.
Best picture(s) I could come up with are these 3.
Knock on wood, I haven't had a rear flat due to a nail or other hole maker in about 100,000 miles. Last one I can remember was on my trip to Alaska, I run over a very sharp flat edged rock, it sliced the tire about 6" across the face, it was a ct. Ms tire would have been a bitch to hold on the gravel. It was instant air loss.
Rock was partially embedded in the ground and I was under acceleration, so tire spun a little and presto, instant slice. Bead never came loose from the rim.
Little easier to see the flap in relationship of the raised front wheel.

Have to look a little harder here to see the flap.

Can't find the picture of the sliced tire. Kind of looked like the heal off of a loaf of bread type slice.