I have been using these
Staun Deflators for over 20 years and they are quality. You can adjust them to stop at any pressure. I have mine set for 15psi, that got me just about anywhere towing the TT on the beach.
I got mine at the Truck Shop in Sayville, not sure if they still carry them. Beware of the cheap-o's that look like the Stauns, they are junk. Spend the $ and get the good ones. Also make sure that you screw them on tight so they seal and you're not leaking air besides what the deflator is letting out. Takes about one (1) 12-oz container of your favorite for all 4 to stop.
Also be sure to remove them and replace your valve caps to keep sand out of the cores. See you on the beach!