So knowing the empty weight is not what your after, its the fully loaded weight you need, and that will tell if you have load margin left for adding the bike rack.We want to know the exact weight of the Caravan, so we can judge whether we can strap on a bike rack on the back
If we are nearing the limit of the upgraded weight of 2000kg then obviously this is a no no.
The Reich weighing system is a great way to go, providing its reasonably accurate. as you can check almost any time you like. You can also check all the essential weights and loads of your entire outfit.
Just remember the whole weight of the caravan is the sum of the weight on the road wheels plus any other point of support such as the hitch or the jockey wheel. which needs to be within the the caravans MTPLM.