Using a regulator is for sure the best way, but i think keeping cost to a minimum is the only way these will sell. A regulator and line is going to raise the price another $40 easy!!
With this you just fill it up to a huge pressure and find the leak, fix that leak and test again. Simple!
Looks pretty damn good to me. Dustin made something similar that he uses a lot and it works incredibly.
His works a bit differently however.
I’m not sure what it’s called, but Dustin’s compressor has a valve in it that will regulate the pressure to whatever you want. The difference is that his stays hooked up and you just set it to say 20psi and keep it connected (his has a direct connection for the air hose built in to it so you dont need to sit there and hold it).
This also lets you test not only for leaks but for how many psi your connections are good up to. I guess yours technically does that also in a less user friendly way.
Just something to consider - maybe going a bit more baller and putting some sort of regulating valve/gauge in there with an adjustment and a connector to took the hose right up to it.
The only disadvantage to Dustin’s method vs. this one that I know of is that his is more noisy most likely and therefor harder to pinpoint leaks… especially if you have a small compressor which is kicking on and off constantly.