Oscar as you say has to be RAC to recover car, but nothing stopping you having Greenflag Mayday to recover caravan which has no size or weight limits above being legal to tow.
Mobility will not allow AA, Greenflag or Mayday to recover their vehicles, plus Mobility RAC Arrival will recover both vehicle and caravan is only £65.00 no size and weight limit, if on holiday and your vehicle breakdown with 50miles of your caravan site they will recover both car and caravan.
Unfortunately I have suffered a brain injury and occasionally I get confused and often say the wrong thing.