You would never, ever, ever fit a bow thruster in there, not in a million years...
I didn't use the kit props, I used a pair of 20mm 3 blade brass props very kindly sent to me by SteamboatPhil.
I would advise using one of ACTion electronics' micro mixers for steering, I was going to use one but funds didn't allow at the time. It steers reasonably well anyway on the kit rudders but it won't spin etc.