I do have a 1/350 Corvette and the brass with it, but after the Tirpitz I am not sure, once bitten, twice shy.
I was thinking more on the lines of what you would see at places like Hornsea, Filey etc where
boats are launched off the beach using a tractor or tracked vehicle. There's usually a shed/building
where "Mr Fixit" works, makes boats, fixes engines, sloshes paint on if asked.
Probably the biggest boat would be no more than 25 ft long so in 1/48 it's within your scope
and continues the tractor theme. Engines could be anything, at that size, commercial engines
with a marine gearbox would be used.
Good excuse for a day out to do some research.
Haddock.