Hi zooma;
You have been doing very good jobs so far with Lesro Javelin and I feel you are facing very serious matters of what to select
for the drive system for the essentially important points for the RCed higher boat.
Here are the pics of my way for my Jupiter F-99(1m long) which is nearly the same length as yours of 39 inch long.
I put here the pictures of my combinations of drive system for the JupiterF-99 only for your reference.
She is a semi-scale cabin cruiser and therefore not intended for speed-seeking boat at all, but intended for a compatible speed with her graceful appearance.!!
1;As for the motor,capable of producing 2200 KV and 1200watts
2;The batteries are 3S 5000mAh class by which she is able to run about/over 15 minutes each and have 4-6 packs.
3;I could enjoy the sailing with these batteries nearly a day including chatting times with some fellow modelers..
4/5;The prop is 46mm dia with P1.4 perhaps???which I'm not sure..
6;She could go on the rough surface of the lake by the north wind in the -mid winter like this.
7;My Jupiter cruising on a calm surface in a certain December..
Please feel the sailing scene and atmosphere by the following video,though the speed is not so fast but I am satisfied with this level as she is not a racer but a queen of the lake at this time.!!
taka's model boat **Mr SKG's JUPITER 2 - YouTube