To anyone looking for the correct answer, it's not possible per se to PC--because it's extremely easy to get any other WEX card (minus the Fleet One Edge) 12 months after getting your first WEX-backed card.
All you need is 100% on time payments during the aforementioned 12 months, and a fresh app in the end for whichever WEX card you desire (minus the Fleet One Edge). WEX will treat you like a pure alpha and wont utter a single peep after the app submission...you'll just get the new card(s) in mail without any approval email or other approval communication.
Your cards wont show it, but the account summary online will list your new account as YOUR COMPANY NAME (2).
Note1: if you still don't have a valid Experian Business credit score, and a DnB Paydex score by the time you app for a new WEX card, then this post is useless to you.
Note2: no PG was ever involved.
Note3: my new WEX card has tripple the CL I had on my first WEX-backed-but-not-on-WEX-network card.
Note4: yes, I realize this finding hardly interests anyone else.