This is more under the category of "a word of encouragement" than it is to help you find a tow tractor
Like you I have undertaken a diorama of large preportions from the 1950s. Needless to say, less than half of what I want to display is available anywhere so I am scratchbuilding (for the first time)
I must tell you that if you look for advise on this forum and do a little planning you will be able to come close enough with your diorama parts that it would be acceptable to any onlooker
My diorama is of a 1956 guided missile launch. I have to scratch build the launcher, launch van, the fuel bowser and rebuild all the figures into Navy uniforms. All of this is from photographs so I'll only be close. So what, it's what I want and that is what modeling is all about
I'd be interested to see how yours turns out - good luck on your build
I'm sure you will be happy with it
Regards,
Richard