As I'm sure you've found, the only pre-made covers you're going to find online for immediate purchase are going to be travel/storage covers with straps/hems (rope) to hold the cover to a trailer.
What you're looking for are custom bow and cockpit (tonneau) covers which as mentioned above are available either DIY OR through an upholstery shop. You can check with your local marina as they may have someone on staff that does that work OR have a mobile shop that will come to them when you bring in your boat. Just be prepared....it ain't cheap.
