There are lenders who will lend on leasehold interests, but these loans are usually kept in house; I don’t think there’s much of a secondary market for them. Look for interest rates that are higher and probably amortizations of less than 30 years. All they’re loaning on are the improvements and the right to control that site for the length of the lease. You might be looking at 10% interest rates and a 15-year amortization; and that’s in addition to the land lease payments themselves.
For instance, a $100,000 loan at 10% over 15 years would have a payment of $1,065/month; that’s in addition to the land lease payment, taxes, insurance, etc..