To quicken the process, pour warm water over your 20lbs tank to increase the pressure. The 1lbs tank will fill quick. Not certain about what the schrader valve on the tank is about.
The US Department of Transportation cautions against refilling 1 lb. propane bottles. Can you do it? Sure... but it is illegal to transport them anywhere in the United States after they are refilled.
I don't know the laws in the United States, Clark, but I would probably it's a no when it comes to transporting. But then again, they sell refillable bottles that are DOT. compliant. Are those legal to transport? I have no idea. I hope someone can chime in on this.
So where is your regulator? I have a inline regulator for all my propane appliances. You are not regulated I guess. Well guess you can run your appliances at 60 psi. OK 💣💥😊😱