If I was setting up a hidden service i wouldn't touch a thirth party payment provider with a ten foot pole (or a 3 meter pole if you're from a country that uses the metric system like me ).
It isn't hard to run bitcoind or a monero daemon on tor and use the json rpc interface to generate new addresses, monitor incoming funds, create new transactions, sign messages,...

If you want to use a thirth party payment provider, you'll probably need to find one that also runs a hidden service, otherwise your customers will be shown an invoice on the clearnet... I doubt they'll be happy about this. I actually doubt your customers will feel safe and secure if you'd use any kind of thirth party payment provider at all... Why involve more people than you strictly have to involve?

This being said: i personally don't like darknet marketplaces... But it's up to you to make sure you follow all laws and rules that apply in your country...