There have been mutiple efforts over the years to make KVOS a "Seattle" station, for obvious financial benefits. When Barry Ackerley owned both KVOS and the Seattle Sonics, he leveraged basketball broadcasts to make sure he got cable carriage throughout the region. Back in 2009, the current owners (i believe) tried to move the COL and the tower down to a tall hill just north of Granite Falls, which would have gotten the signal as far south as Tacoma. The feds said no to that move.
The heyday for KVOS is way back in the rear-view mirror. It did its best when it could sell ads into the Vancouver market (they had an office and fulll time sales/production staff in Vancouver) as a US indy staiton- we are talking the 60s and the 70s. Once the Canadian government dropped the bomb on advertising write-offs most of that money quicky dried up. I love living up here, but there's no way that Bellingham can support a full power station with actual personnel by itself.
In the days of analog, you absolutely could get KVOS on north facing hills in the Seattle area. My aunt got it fine on her big antenna on the Renton Highlands. When I was a little kid living in the Edmonds bowl, I got my cartoons on Frisky Frolics on KVOS.