Hi Bob and welcome to the forum. I would just like to offer a few words of caution regarding your Alte Liebe project. Both the build and operation of model with a steam plant in an enclosed hull is quite a bit more difficult than an open hull. Space is usually more limited so the layout design requires far more thought and ventilation and access both need to be taken into consideration.
Possibly the biggest challenge however will be the operation and getting your hands inside an enclosed hull is always that bit more difficult than it would be in an open hull. Being new to model boat building I think it is very important to start off with something as easy as possible to use as a learning platform to find your way around how the plant operates and what auxilliary bits and pieces you may wish to include. The things you learn from the open hull experience will be invaluable to helping you design and build the enclosed hull model.
I would suggest that you start off with a kit where everything has been designed for you and put a complete manufactured steam plant in it to keep things as simple as possible. You could even remove the plant and put it into the tug if you wish. I have seen many modellers start out with an enclosed hull and come across difficulties that eventually put them off completely and they end up with a very expensive half built project.
I'm not saying it cannot be done but do your homework and be very aware of the challenges you will come across.