Sounds like you know what to to tepples, go right ahead.
Is there enough room in the NES internal RAM to do all that?
You can have any graphics you want until you swap carts, selecting mapper manually perhaps and so on, maybe set and be able to test dumping speeds instead of doing it blindly and then send the whole cart out in a single sweep maybe including a proper iNES header as well. Everything would be set in RAM and then you'd swap carts.
That rudimentary text by using a filled or the most filled char could be used after that I guess for better information in case someone has trouble seeing colors.
Great start here anyway, the idea is brilliant, I hope it's developed further and that everyone who likes it also registers here and leaves a comment.