Hi Stan. I don't have a safe system of work for such a task but was involved in the provision of risk management services to what used to be a fairly large holiday parks business. I recall addressing this issue during a number of visits and was surprised at the general lack of coordination for moving the caravans.
We did however agree on some fundamental requirements:
1. All services must be isolated prior to ANY movement
2. Suitable supports must be positioned under the caravan prior to the removal of any skirtings and drainage disconnections
3. The move would only be undertaken with the presence of a suitably competent person
4. NO ONE was permitted under the caravan unless physical and suitable supports were in place
5. No attempt would be made to move the caravans in high winds
6. Someone would act as 'look out' to keep members of the public from the immediate area

Hope this helps in some way

I would suggest contacting the caravan maker.

If not, there are a lot of static caravan parks around that they must/should/hopefully have a SSOW. contact their SHEF advisor. If they are part of a larger concern (Cinq-ports springs to mind) then should be no problem sharing.