I think everything else is ok. I'm not an expert and I did not stay at a Holiday Inn last night. Your stainless steel guide rod probably adds weight over the stock plastic one, so take that into account as well. An indoor match will probably have shorter courses of fire so you could be ok with 40 rounds in your 4 G19 mags.
Remember that on any stage where you start with the gun loaded you can start with one in the chamber and 10 rounds in the mag.
Have fun and be safe.