Those are good numbers and a bit better than I've experienced with my Highlander. Mine runs similar speeds but i need to run higher rpms. But I have wheel skis that are open tube with platic bottoms. The Summits you have look a few mph cleaner. And your Clamar floats compared to my Cz1300 amphibs also look a bit cleaner (my wheels are larger and I have 10,000 rivets in aluminum vs yours being smooth fibreglass).
Interesting to hear about your airpark lot purchase. I bought a lot at Mount Royal Airpark in Crescent City Florida a couple years ago with a similar plan as yours. Being right on the 360 mile long St Johns River which is also attached to a 43,000 acre lake, and surrounded by literally thousands of open-to-seaplanes Florida lakes, it will be an awesome place to fly seaplanes. Ironically, a bunch of my seaplane pals from here in Wisconsin all bought lots near me at the airpark. So once me and my friends retire one day it will likely be a great place to spend winters. Of course, ski flying there will suck

But that's ok as we all agreed we will continue to spend summers here in Wisconsin. This part of the world is great when everywhere else is uncomfortably hot.