This may not be cost effective, but I *think* Plastiq accepts pre-paid cards (or so their website says):
" We are proud to accept all credit, debit, gift, and pre-paid cards with the following brands: "
You could buy pre-paid MasterCard's on your visa card, then use the pre-paid MC via Plastiq.
However, you'll pay the pre-paid card activation fee (sometimes there are sales, etc., check the Manufactured Spend forum).