I my experience, it is very difficult to get a nice sharp image from a template and spray, especially on a smaller scale. It would be fiddly anyway to make the template.
It the hull is white, and you dont want to splash the cash, then you MAY get away with simply printing the appropriate lettering on white paper, trimming tightly and pasting this on the side, and varnishing the whole hull afterwards, so that the paper has the same gloss as the rest of the paint.
I dont know how much this "DIY" transfer paper is to buy? you just print your logo`s on to the stuff and cut it out and use it like a waterslide transfer (so I have read!!)
OR just use (Black?) sticky letters, easily available in print shops, or art shops, or even larger newsagents. Not expensive, couple of packs should do you for the duplicate letters.. not too large the letters are they?
Ashley