My best friend lined a very big closet with what I think was Eastern Red Cedar.
He got nasty headaches from cutting it.
Upon inquiry, his supplier said it was toxic, and he should have been wearing a respirator.
I'm guessing that's why the bugs avoid it.
Exposed rafters do not sound like a good application for it.
I do love the spectacular coloration and grain.
Maybe you could make the actual rafters from a less aromatic wood,
and apply the ERC as a veneer, sealed with a heavy coat of something clear
on all faces and edges.
The rustic souvenir industry produces a lot of trinkets from ERC
or similar, with a glossy thick finish like decoupage.
Mike Halloran
Pembroke Pines, FL, USA