There were many times when I wished sawhorses were a little higher, or even a lot higher. To solve this problem I built some with an adjustable top bar.
I made the top bar longer than the sawhorse base so the aluminum support rods, which are epoxied into the bar, would clear the legs. I drill the holes for the 3/8” diameter rods slightly oversized to make adjustments easy. The rods are marked off in 1” increments with a heavy felt tip marker so I can quickly adjust and level the bar. I anchored 1/4” – 20 threaded inserts in the base, and used 1/4” x 2” – 20 thumbscrews to hold the bar at the desired height.