I don't use a TMPS, but I do see that the TST is the most popular unit out there.
Unless you have other uses for an air compressor, you may want to rethink carrying one. I've carried this one,
Porter Cable for over 10 years and have only used it once on the road, on our last trip. Someone parked next to us had a flat. Other than that, I've only used it at home to fill/check my tires every four months.
You shouldn't be needing to add air on a trip unless it's a trip of several months. So don't buy something that's overkill if you decide to carry one. The Porter Cable above will add about 1 psi every 13 seconds to a 22.5 tire and will go to 125 psi.