We came from 50+ knots, lake boating, and for us 35-40 knots was slowing down. I'd recommend some chartering of different type boats. We chartered one 12 knot boat and while the boat was incredible, we couldn't live with the speed. We found a 20 knot cruise to be the slowest we were comfortable with. That was still a huge step. 7-8 knots just wouldn't work for us, nothing wrong with it, just not for us.
I don't think those who haven't come from faster boats fully appreciate the issue you're facing. You may need to think outside the trawler box a bit. Sea Ray is definitely an option, although the express styling not as conducive to long range cruising. Still much more space than you are use to and Sundancers are very good for your cruising grounds. Eastbay and the type are worth considering. Sabre. But also Hatteras, Viking and others of that ilk. Then if you want to think outside the box, look at boats like Sunseeker, Princess, etc. In the 15+ knots cruise, Beneteau Swift Trawler works, Grand Banks.
Only you can tell what you could be comfortable with. I am guessing a cruise of 15 knots plus. You could try a few days at that speed on your current boat. But I'd still recommend chartering. After one week at a slower speed, you'll know if it's ok for you.
Now, you've had a glimpse at course 102, back to 101 for a moment. You need to define your requirements. What are you looking for in this boat. Sleep how many? Flybridge? What type galley? Indoor vs. Outdoor space. Draft. Air draft. Speed is just one factor. What are you wanting it to do for you. I'm assuming also you're keeping your land base. Two boats might be the solution. One like your present, one slower and larger. Maybe even tow a boat like you have now behind or something smaller.