That's the proper way to check POI, Jim. Squirrel aiming is a local colloquialism for steady aiming the shotgun like a rifle, before shooting. That doesn't always yield the best results for POA/POI testing, IMO, as poor fit can be partially overcome by aiming. But, what you want is the same mount/shoot you will have when hunting.
Tape and wedges will work for testing. I have had buttstocks built up on the comb with cardboard and duct tape, put flat washers under the buttplate, all kinds of temporary tricks to try and learn more about how to change POI. Fun, if you have the time.
Good luck, SRH
