Getting back to the original topic, I don't think Tony was suggesting that he wants to transfer payload from caravan to car in order to achieve an actual 85% weight ratio because the calculated one based on MTPLM and kerbweight was much higher. Firstly, there is no recommendation for actual weight ratio, only for the worst case condition. Secondly, even if the standard calculated ratio were 100%, the actual weight ratio can easily be a lot less than 85%.
For example, if the kerbweight of the car and the MTPLM of the caravan is 1500kg (i.e. a 100% weight ratio) and you transfer the bulk of the payload of the caravan, say 200kg, to the car, then the actual weight ratio will already be reduced to 76%, even before adding any passengers and their luggage to the car. Once they are on board, the actual weight ratio will be even lower, probably under 70%.
Conversely, if the car is fully laden and the caravan almost empty and the actual weight ratio in that condition is 85%, I shudder to think what the weight ratio based on kerbweight and MTPLM might be (probably in the region of about 120% and as likely as not outside the specified towing limits!)