So you're giving an admin account as collateral... But what's stopping you from revoking admin access as soon as somebody gives you the funds?
It's still  hosted on your hosting, you're still the owner of the domain...

I would never take a domain as collateral, but if i would ever accept one as collateral, the only way would be to transfer the domain to a trusted escrow together with actual paperwork, so the escrow can either transfer it back to you if you repay, or transfer it to the lender if you fail to repay... It would be a hassle, and it would be hard to determine if your domain is actually worth >$1500. In my experience most domains are greatly over-appreciated by domain appraisal companies or domain owners, but if you actually want to sell a domain either nobody is interested or the price is a LOT lower than the estimated value.