...Hi Zephyr...
I would recommend a "NANGEE" hull from Mobile Marine Models...At 28" long & just over 9" wide it is ideal for a good Towing/Steering Tug...
It can be built either Single or Twin Screw...
I have built about 5 tugs using these hulls...There is a build blog on the Forum of my "SCOTCH PRIDE" build...
I hope this helps & All The Best with your project...
..Best Regards...Norry...