It's not designed to pass big data back to server side, map need to pass necessary data itself. If you want to do extra data operation, you should want to implement that by custom code but not via map.
And in fact you can try to implement it by a simple custom function just like my suggestion. Loop the parameters, split by special delimiter and get the information you want.
We still thanks your suggestion about our product, maybe we will provide some helper function for pass the data in future.