We're working with a builder. Interviewed several, got references, lots of other due diligence. He's done several waterfront builds, including one on our peninsula that was completed last year. The homeowners invited us in for a tour and had tons of praise. Sounds like he's got a lot of the supply chain issues pretty well sorted out - knows when things need to be ordered, etc.
Our architect is doing the permit submission package, and it will probably take about 3 months to get approval. So in that time we'll be finalizing our finishes and getting ready to order.
I also did some more research on the heat pump low temp efficiency subject. Looks like in the last 10 years or so, there have been big efficiency improvements, and plenty of units that still have COP around 2, down to single digit temps. So maybe a COP of 3.5-4 at 40 degrees, but still around 2.5 at 20-25 degrees, so I think we're good there. An electric aux heat wouldn't kick in until the heat pump drops below COP = 1.
We'll probably be doing a power wall, need to research incentives from the new bill. Will be doing 400 amps for the house, having garage prepped for EV charging, probably prep for a generator transfer switch, things of that nature.