A time honored method of applying a low psi safely into a small volume (forks) is to pressurize an air tank to the desired psi and use that to load the forks. Maybe need to load the tank 1 psi higher. Accidentally over pressurizing the forks too much, which is easy to do with a compressor, can do harm and is tricky to adjust accurately. As with many good solutions, credit goes to Dave F many years ago.