Well, this is not a solution!
I want the customer to select the amounts of week he wants to rent the object. Minimum renting time is one week, but if he likes, he can rent it for 5 or 27 or 46 weeks. Its not suitable to create hundreds of reservation types. Also he should get some discounts in regard of the number of weeks he is renting the object.
Additional problem: If you have a reservation type with fixed amount of days. The frontpage still shows the button with the request for the "select end of booking period". Selecting this causes an error massage. This is confusing or the customer!