[RS]

I don't think there is an inherent turbulence issue. It just seems that there is not much board experience with the best place to install a thru hull since others found easier ways to install a transducer. Also, since this group is restoration oriented, there may be an general bias toward not drilling holes through the hull unless there are no reasonable alternatives.

To actually answer your question about the best place, common wisdom is that thru hull transducers generally work best on planing hulls toward the transom and on the deepest flat section of hull. This would be about midway between the keel and first vertical rise.

Also be aware that your fairing block may not fit properly if the deadrise at the installation location is not the same at the prior boat's.

A final thought is that a through hull affects trailerability of the boat, which might influence a future sale.

Hope this helps.