Check out Affirm, super easy to use with the app. I know at the very least kellyco accepts Affirm, I'm not sure about the forum sponsors, but I wouldn't be surprised if at least one offers something similar.
I've used Affirm a few times now and you can use it anywhere once your approved, as long as your dealer accepts credit cards Affirm will send you all the info for a pre paid card for the exact amount of your purchase.