I don't want to encourage anyone to go beyond their own capabilities or boat's capabilities but saying that, we used to cross the straight to fish Active Pass and around Cabbage Island when I was younger in 12' Lund with a 10 horse motor with my father in law who's family had a trailer on the water at Bells Point Roberts. The old timers over there were doing that for long before that as well going back to the 70's. This was done only on the calmest of days with the best weather reports. Would I do that again? No, never. I've seen the weather change much too fast over the years all around the coast and have been involved over the years seeing lot's of what can go wrong out on the water and have had friends lose their lives on the water for these exact reasons. Looking back I can't believe those old timers did it for so may years but they were seasoned fishermen that lived there for a portion of every year and knew which days were going to be good enough to cross on. I had heard too that on occasions some of them had to stay over or get picked up by bigger boats when the weather did change on them when they were on the other side.
When I owned my 15' K&C fiberglass boat with a 50 on it I used to cross from there as well a fair bit on good weather/water condition days but I was very used to the straight and only did that on very perfect days for it and never over stayed on the other side. Fishing was a lot better back then too around Active Pass which made it more enticing to go. We always went with other guys in their boats and we had 2 way radios back then and the VHF's. No cell phones back then. There weren't such things as safety beacons etc back then either.
Any mechanical problem and your stuck at the mercy of the weather/water conditions. And when the weather report calls for 15 Kn you can bet there will be gusts up to 20 for sure. Open bow, low stern, and non self bailing deck boats are going to be much more risky when the weather and waves pick up. And in the straight it's common to have stacking waves all mixing from different directions which makes it even harder to keep water out of your boat.
Only takes a split second for one good sized wave to come over into a boat that's not made to deal with it to sink it.
In this video I was crossing the straight after a bad storm that just started to brake up a bit. I was coming back from a trip up to Lund. I crossed over to use Texada as cover from the direction the wind and storm was coming from on my way back. By the time I came out of refuge in a bay from the storm to cross back over the winds were dying down to around 15 to 20 knots but you can get a decent idea here how the water can get a bit nasty even at 15 to 20 knots. The water conditions the morning before this was glass calm.