Suggestion Box

I think there's a way to handle that but you'd have to test to be sure because I've never done it
If the forum is group only, then you could set the "Group Only Posting" in "Item Type Specific Settings" at the highest level which I assume is you.
If the item is not, you could create a mock "group" with you as the only member and use those settings.

Give it a try and let me know!

Leger~