When I tried to use my Swagman hitch-mounted rack on my 2000 Honda Odyssey minivan, I had to be careful to keep the bikes from dragging.
I debated having an extension welded to the upright, but decided to take a less destructive approach. I went to a local trailer store where I bought a short hitch with a drop / rise. Normally it’s installed to lower the mounting ball on vehicles with high bumpers.
I needed it to work in the opposite direction: to raise the mounting point on a low hitch. I mounted the hitch upside down, so it was higher than the original hitch. This picture shows a comparison between the original hitch and the new one. The extra height made a big difference.
I eventually replaced the traditional trailer ball with a bolt that was easier to tighten.