If the trailer is reasonably heavy I see no reason to mount the machines on rubber mounts. That could cause problems when moving the trailer around. Good solid mounts and a stable trailer would be the way to go IMHO

BTW the trailer is on its own rubber mounts 🙂

One part of my employers business is mobile workshops for the military. They tend to be in ISO container compatible packaging. I get involved in some aspects of these. There is no resillient mounting of machine tools in these. Set the “workshop” level and level the machines to the same level.
You could consider a small ISO container but budget to fully insulate and line it oryuo will have terrible condensation problems. Moving it will cost a bit more when the time comes but it will be a better workshop.
Withem Specialist Vehicles often sell MOD surplus moble units https://www.mod-sales.com/
They have a couple at the moment but the existing “machines” are not what you want…
https://bid.mod-sales.com/auctions/9024/witham10160/lot-details/3de34fde-42fb-4aaf-b69e-b1d900bd62c7

Robert.

I cannot see what you thought rubber mounts would help with unless you intended to run the machines while moving down a farm track.
What you might consider is putting each machine either at the feet or the bed on some kind of frame that provides only 3 point mounting to avoid any flexing of the trailer being transferred to the machine which could in extremis, crack the cast iron.  Interested to hear if the army workshops take this approach.

Containers are very expensive to have moved, can be 50% of the purchase cost.

Early Southbend lathes (Hercus in Australia) were used by the army, often in mobile setups and the recommendation was to mount the lathe on 3 points. Headstock bolted down at 2 places and a central point on the tailstock end that could pivot.

My first thought was whether this ‘cattle trailer’ was new or used.

If used, I would be carefully inspecting the frame/chassis of anything that has had animals in it, before mounting heavy machinery in it.