I used to run my warships on the Willamette river decked out with Christmas lights.
The water is typically high and the current quick at that time of year. The two boats
did alright with twin three blade propellers. The DD had 1.5" propellers and ran on
two Dumas 4.8volt motors and a 6volt gel cell battery. The Cruiser ran on 2" three
blade propellers and Pittman motors. I don't think either set up (both direct drive) ran
over 10,000 rpm.

It was always fun to run upstream, slow the motors till the ship was stationary on the water, then
flick the rudder and let the current sweep the bow around and race down stream.

I don't think you need to run five bladed props. Three or four should run fine.
You are trying to get a hold of a Thompson trawler right?
Is that single propeller or twins?