So... have you actually checked with your CLEO yet to see if they will sign-off? If they will then no problem. If WI law say a WI trust needs sign-off then try this (talk to a WI attorney first):
1. Open a "small" PO BOX in MN
2. Change all addresses in your trust to the address and county of your PO BOX and all references from WI to MN
3. Go to a Wells Fargo in MN with your trust and co-trustee and have them (Wells) notarize your trust (now you have a MN trust)
4. On your ATF form, put your PO box as the address of the trust and your WI address as the physical location.
I just mailed off my paperwork to the ATF to register a SBR. The trust address is my MN PO BOX and the physical address is my home address in MN. I had a NV attorney familiar with NFA draft my trust (I had to make corrections to dates etc... so read yours closely).
WI allows ownership of NFA items and so do the feds with a stamp. The ATF form 1 allows for mailing address and physical address and there is nothing I have found or seen that requires them to be in the same state (I am guessing the ATF cares most about physical location anyway). It is legal to own or manage a "legal entity" in another state so logically this will work. It wouldn't be any different than if I took my MN SBR & MN trust DOC to WI for a weekend to shoot - cops come I am legal. In your case, you live and shoot in WI, cops come to inspect your papers - ATF stamp, MN trust & no CLEO signature - no problem. If the law or AG findings specifically spell out "WI resident must have WI trust and CLEO signature" then you are stuck. If the trust doesn't have to be a WI trust you might have some wiggle room.
Again - if the head cop will not sign, talk to your WI attorney about loopholes. Worst case... do the MN trust and in 7 months the ATF rejects your trust and refunds your $200.
Not sure what else to say on this one other than... don't be a test case