I suggested a brushed motor as its easier to specify the size you need. With brushless you have to consider more factors, plus these were originally designed for aircraft use where high revs are required, and they only have to go in one direction. Things have improved a lot, and some now have good slow running capabilities. There are now some good waterproof escs offering forward and reverse - avoid the car ones as they have a brake function which can be a problem.
I have used a brushless motor in a small model, and I think the combination I used would suit your models, but I can't be sure. I used a 1000Kv motor and a 30 amp marine ESC. I can supply details if you wish, although I did buy from China.
I am no expert on brushless!