See the following links for publications and a spreadsheet on flex leases. They are provided by Greg Halich, an Extension farm management specialist with the University of Kentucky.
By visiting these sites you should get a good idea of how you could build a flexible lease that might benefit both you and your landowners. Given the current low prices, it could help you buy time and cut out some red ink right now.
The landowner will benefit if and when crop prices return to higher levels.
Ag decision maker: Flexible cash rent lease examples
Flexible lease agreement worksheet - Actual rent
You may also find it useful to check out various crop budgets as you work through preparing a flexible lease.
Start with this budget from the University of Kentucky.
For more information contact your local Extension educator.