Thank you flatliner, been working on a design myself working around what I can get in town needle valves are hard to come by here but I think I've got something that should work. I can't draw but here's what I have.
A 3/8 flare ball valve connected to my regulator, connected to a 1/2x1 1/2 pipe nipple connected to a 1/2 inch tee. 1/2x1 1/2 nipple connected to a 3/4 to half reducer, connected to a 3/4x1 1/2 nipple, connected to a 3/4 glove valve duct taped to a coleman air mattress pump. On the other side of the tee will be a 1/2x 1 1/2 nipple connected to a 1/2 inch elbow, connect to a 1/2x1 1/2 nipple, connected to a 3/4 to 1/2 reducer