Determining parameter length of methods

I am trying to implement code that can connect to several different SAP systems using the .NET connector.

Unfortunately, for some functions, the SAP systems might have different number of parameters, or possibly different lengths of these parameters (seems like this is possible). I'd like to be able to check this at runtime.

For example:

In one of the systems, BAPI_IPAK_START only takes 3 parameters instead of 4. When it only takes 3, the parameter it does not take is job name. I've noticed if I use the proxy with 4 parameters, job name just gets ignored. However, I need my code to have a different behavior when there are 3 parameters or 4. Furthermore, when there are 4 parameters, I'd like to be able to check the allowable length of "job name". (1 reason of several: I can limit the input text length in our UI appropriately.)

I don't want to generate a whole bunch of proxies for a bunch of different systems, for rather obvious reasons that is really unacceptable...