Better than a false cut in your roof. Gotta say, this project scares me.
Chalets are sold to rental fleets. It's very possible that the fleet yours went to had deleted the roof vent. I saw sale orders for Chalets that had things like Front Window Delete, Rear Window Add, Awning Delete, Shorten Rear 4" Tubing Bumper. Somebody might have thought a renter would leave the vent open and let a rainstorm in.
We can hope that another owner has dealt with this or has a 24 with the vent and could give you measurements. Make sure their A/C is ducted like yours.
And... Great Alaskan Holidays in Anchorage is major rental outfit that buys bunches of Chalets. Also a Ford, Winnebago, ONAN warranty station. Pretty squared away. Call 907-248-7777 and see if somebody in service or fleet buyer can help you. Maybe they'll have a back channel to Winnebago...
