Depending on the access, maybe you handle the whole thing from land?
We have a Genie telehandler on my jobsite right now that has the capacity. This is the one, but there are others out there.
https://www.readyeq.com/product/geni...lehandler/5139
This could pick it up, get it to the water and possibly even extend it out a ways and drop it in. You may still need a diver to float it with airbags to where you want it to go, but thats easier than getting a marine construction company right now.
My other thought would be to call Moore's Crane in Dover. They could easily rig and lift it, swing it out and drop it in. They have lifted the Dive, MB Tractor guys big boats, and even lifted hot tubs over my house a few times.