I carry a P365 (standard) every day with the 12rd mag in pistol and a 15rd in a side car. I added a Holosun 507K red dot. If you ever think you'll get a red dot, get the P365X which has an optic cutout already. It saves the hassle of sending your slide off to be cut and re-nitrided.
The up lula posted above is a must for loading the mags to their full capacity, but only the first couple times, after you've loaded them and let them sit for a few days, they can be loaded by hand. It does still get a bit tight at the end, but doable. The up lula is a fantastic tool either way.
I wouldn't buy the tac pac, the holster that comes with it is atrocious, and a standard 365 comes with two magazines, so you don't get anything fantastic for the tac pac price.