The CRIS number is usually just the VIN so let's drop the reference to CRIS number.The CRIS number is shown on the sticker on the body of the caravan. and we are all aware that CRIS is not a requirement The statutory plate is supposed to have a TIN number on it as a trailer is not a vehicle.
However this does not help the OP who has not confirmed whether it is the sticker on the body of the caravan or the statutory plate that is fixed to the chassis that is missing. Also year of caravan would be helpful.
I've not seen the use of TIN except in your posts, it's universally referred to as VIN as a trailer is a vehicle, albeit not a motorised vehicle.