I use and old fashion tire gauge where the scale slides out. I have one I bought in the Sixties that is plus or minus a one psi accuracy. I only trust any digital measuring instruments if I have a way to set zero and span. Meaning if you don't have a way to check the digital gauge for accuracy at the pressure you want to
see, you might as well be using an old fashion gauge.Plus an old style gauge will be more durable to abuse and take up less room in your box than a digital and there is no battery to go dead.