Selling with temporary lease?

[Nick Q.]

I just finished rehabbing a house and have someone wanting to buy it. The catch is they want a temporary lease until their financing goes through (30-60 days).

It is a large property, 3,670 square feet, where a lot of damage could potentially be done.

How would I write it into the contract where I get a large, non-refundable down payment (eg: $5,000) to ensure that the buyer has an interest in closing quickly and not damaging the property?

This is in Texas.

Thanks.