I ended up staying in Shopify in the Shopify POS app. You can make a sale
and allow for partial payment. I then have to manually (set a reminder on
my calendar) email the customer (say once a month) and call them to get
their credit card info and make another partial payment that way on the
same “sale”.
By no means ideal, but it has worked for me. Very little of my sales are
done this way, so it’s a workaround that I have to be okay with.