Perhaps when getting a loan against collateral, they could tax the value of the collateral. Make it so the loaner cannot receive more than they declare the collateral worth ( which should prevent overly low valuations by making them a risk to the loaner ), and require the loanee to pay taxes against the 'loan-value' of the collateralized resource.

Treating the lien itself as something created by the loanee and sold to the loaner, I suppose.