Keystone Cougar - Installing 2nd AC - Roof cut

I think I would have done dicor over the cut prior to mounting the AC, then cleaned and sealed the edges of the AC cover with eternabond after a week or so.

Dicor is a great sealant, it just doesn't have the staying power that Eternabond does, needing touch up after somen weathering. Eternabond is super sticky, doesn't come up easily and is a nearly permanent fix when applied on a properly cleaned and prepped surface.