Expense Report Fields To Not Require Null Value

The expense report view has several fields such as the following:
Purpose, City, Comment, Description, Related Products, ,State, Vendor
Some fields like the comments field accepts a space value.

We would like to configure the backend so that it requires at least a minimum of 1 character (with the exception of <space>) for all expense report fields visible in expense report views.

Please let us know if this is feasible.

Thanks.

Cryssal