I never got into motorcycles when I was playing Classic Car Wars. I always assumed that when you added a sidecar with a seat you got to add a gunner.
And all open top Jeeps have an MG pintle mount. ;)
I guess I was overly influenced by Rat Patrol, WWII movies and 12 inch Gi-Joes.
Any way, here's a link to an informative article. There are even some pics of Motorcycle Sidecar Trailer combos.
https://autowise.com/ww2-motorcycle-sidecar-bikes/