Sorry, the answer is actually “no” unless you are a DM and can spend DMC.I know non-DM's can only have two active characters, but could I make some extras and have a 'stable' of characters I could pick for adventures? I know I wouldn't advance that fast overall level wise, but I have a few personalities I'd like to try out.
Right because DMs are an exception, GE.I think the answer to that is yes (but maybe I think that because I'm actually doing that).
Yeah, I don't think that will apply here. No one is sitting with a stable of characters all the same level.The only cautionary note I have on the subject of having a 'non-active' character in order to have a choice of characters for adventures is it can invite the practice of meta-gaming the character selection process for personal advantage. I've seen that overtly in Pathfinder Society and it leaves a bitter taste in my mouth.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.