Just finished a setup for a friend. Axis alloy mast, Flipsky 6384, 75200 esc and two 10S3P BAK 45 packs. Meant as an efoil for learning on a 125L wing board with the motor at 2/3 of the way down the 75cm mast.
As he improves and if he wants to we can spin the mast around and re route the cables so that the motor is 25cm below the board instead of 50cm.
Box with batteries will sit behind his back foot.
10S decision based a little on past experience that with the 140kv motor and twin regular Foil Drive black props the speed available is more than most people really feel comfortable at anyway.
Had an acetal plate machined by PCBWay, all cut to shape and pre-tapped to accept four screws to secure it to the mast and to accept the cable clamp.
Really happy with the way it turned out, the cable exiting the mast has always been the weak link, prone to having cable damage and looked amateur.
A lot of work to get it all right, he’s a good mate 
Also tried to up my game a little with the battery building on this one. Printed shallow trays and sat the welded completed batteries in the tray and covered the terminals with silicone. After it set, just trimmed back with scissors before wrapping. Hopefully another layer of protection against any moisture in the box or even a more serious box flooding.
My experience with making setups for friends is that with the best will in the world they aren’t as fastidious about moisture, cables stuck in the seal of the lid etc etc.
