Hull selection for buoy design

I want to make a rigid buoy for spearfishing which I would like to have the lowest possible resistance and be able to carry a weight of up to 12 kg of which 8 will be a lead weight that will hang under the buoy.
I thought that the most effective form that the buoy could have would be a miniature sailboat with an 8 kg bulb that has such displacement that I can load another 4 kg in the hull. I would also like the length not to exceed 1.4 meters.
I would like to ask you if anyone can suggest me a hull design with the lowest possible resistance who at 1.4 meters can lift 12 kg (excluding the weight of the hull). From the designs I found available I really liked the VO 70 but I do not know if at 1.4 meters it can carry this weight.

Have you considered using an RC-fishing boat design? Like the ones below, without all the gadgetry.
Or the remote control lifeguard?

These designs seem interesting. But I would prefer the hull of a sailboat because I am looking for something with the least possible resistance.