Many years ago, my father hired a tree service to remove some huge oaks that fell into the lake on his property. It is an oxbow lake, about a mile long, but only 100 yards across, and the bank is too steep and 90' high, so no getting down there with any equipment other than chain saw. No way to get the logs up the hill.
There's a park across the lake from the property. The tree service somehow got the Army Corp of Engineers involved on "a training mission". They drove a 5 ton 6x6 truck into the park, used a rowboat to pull a rope across to the trees, then used the rope to pull cable from the 5 ton truck's winch across. Attached it to the large oak with twin trunks. The truck had no problems winching those two trunks across the lake, stumps and all. The only issue was they had to use an extension cable because there wasn't enough length on the winch. When they'd pulled in all of their cable, they just put the truck in reverse and backed up, pulling the trees the rest of the way across.
Just something to think about.