That is a really excellent idea!
A way to deal with the pure reliever roster requirement problem might be to create a custom set that includes simply ALL the pure RPs priced below a certain point. This maximum might be .99M, for example, or perhaps lower. One could, of course, set the limit higher, but that might lead to non-NEL players having too large an impact on the games.
Anyway, custom player sets aren't that hard to create if someone wants to take a crack at it.