Using Your Spot as a Collateral in Futures Trading?

The spot future's arb. can be used as collateral, even if the trade should close profitably. The idea of a joe transacting with you actually reminds me of a question that i wanted to ask, which is, how do you manage your counterparty risk? There are a lot of sketchy players in the crypto space. How would you go about doing due diligence on a potential client? And does it differ from like a hedge fund or an investment bank for something more traditional such as prime broker services and finner regulated trading. I think what josh yonger brings up is really, like a a liquid point of access for similar in the brokerage model, like the