Fee Schedule - Possible to charge more fee for later expiration date?

[abitmore]

Market orders and proposals have an "expiration" field, which means the data will remain in witness nodes' memory before expiration, which consumes resources. I think it's reasonable to charge a fee if the expiration is too long. For example, with current fee schedule the maximum expiration period is one month, if the owner wants it longer, she need to pay 50% more for each extra month or so in advance.

[xeroc]

Not sure if this is making things too complicated already ..
But I like the idea. We could even require users to be LTM if they want an expiration time that is above x