As previously stated, the universal fit covers sort of fit. The problem is they generally make the cover to fit "todays" boats beam and transom widths. Very likely your boat is a few inches narrower than they are today. That was one problem I found out some years ago on a different boat.
The boat I have now came with a Sunbrella type fabric bow cover and cockpit cover, it snaps into place. That said, not that good for towing.
So I went to a place that made me a travel cover out of the same fabric I had my two previous covers made from. The fabric is from Marlen Textiles and is called Top Gun, or the latest version I have on my boat is called Top Notch.
The folks that made the cover used all the original snaps that were used for the previous top, they had to add about 6 extra snaps on each side of the bow.
All 3 of the covers I've had are bomb proof. I can tow at 70 mph into a stiff wind and the cover hardly moves. The thing is, the cover has to fit like a glove and be practically drum head tight, which also means the fabric can't stretch. That would be the case with the Top Gun/Top Notch fabrics.
I tow our boat approx 280 miles round trip 1 - 2 times per month, from May to October, so having a bonafide water resistant travel cover paramount. Here are some reasons why.
1. The boat tows a lot easier. Without a cover it tows like a parachute. With the cover it's like a bullet going through the air.
2. I don't have to worry about a rock chipping or breaking my boat windshield.
3. I don't have to stow EVERYTHING so it doesn't fly out of the boat. Cover up and go.
4. The interior of the boat doesn't get wet and full of road grim when towing in the rain.
5. It keeps an honest person honest, , , at least in my mind. I've known folks that were going up fishing, they stopped for lunch and when they came back to get on the road they were missing rods, and a few other things.
So yeah, I'm all about a custom travel cover. BTW - I had this cover made early in the season so I got early bird pricing, $950.00. Normally it would be another couple hundred bucks.