do it yourself, it's really not as hard as you may think.
All you need to do is-
1. mark off where you want the opening
2. Real important to install a couple of temporary supports to each side of where the walkway will be.
3. start cutting with a sawzall or a scroll saw.
4. once the opening is cut, cut and fit plywood bulkheads and glass them in.
5. use some cardboard tubes (like the ones inside Christmas paper but thicker) and glass those under the bow where the opening is cut.
You can now either build your own seat frames/bulkhead covers or bring it somewhere to have done. The upholstery will cover all the cuts.