Proposed route from Creston BC to Prince George BC

That is a very scenic route but take your time, it ain't your average interstate. We traveled the southern portion last summer and thoroughly enjoyed the trip. You won't have problems on the ferries but you will be required to shut the propane off.
An alternative would be north to Golden then west through the Rogers Pass
. At Kamloops you can go north to Tete Jaune but the leg from McBride to PG doesn't offer much scenery wise.
Edit: The roads are all paved and in good condition.