This is already done by the construction and other seasonal industries.
And honestly, for the case of a construction worker, where working outside in the winter may not be feasible.... it makes sense.
Yes, some will work the winter. Some wont.
IMHO: Preventing abuse of UI is impossible, just like preventing piracy. All we can really do is make sure that the people who should get it, do.
Also, taking a severance package shouldn't impact UI. etc. All silly stuff. We want people with max incentive to apply to jobs and rejoin the workforce. The way we do that is keep them able to work (not homeless), and make them look for work... sounds like unemployment to me ;)