First, ask if the "22LR friendly" match requires a holster for a 22. Might not. Regardless, you would need extra 22 magazines.
There is a fair chance you could borrow 1911 single stack 45 mags at a match, but 5 of 8 rounds should be ok. I am not sure what "USPS" is, but USPSA allows 10 round single stack mags, but it is a different division. No big deal, means you do not need to buy as many mags.
Stuff mags into the mag holders, and let sit until the match. Also work them some to smooth and/or loosen. Not too much, be patient.