You have a few options that will get you some of what you desire.
To send the customer correct geometry for interfacing you can send a dumb solid. You can also save out the assembly as a part file and keep only the exterior surfaces. These will not be parametric so if something changes then you would have to generate another updated version of the dumb solid to send to the customer.
You can use Insert Part for some situations. I use this for machining a casting where the casting part is inserted into another part file for me to do the cuts on for the particular machined version. If the casting changes then the machined part file is changed, but I cannot change the casting from the machining file. This is really handy for not only castings, but also for overmolding and die casting.
There are others items that might be of some benefit to your efforts such as SpeedPak, but you'll have to read up on that or contact Alin Vargatu as he sounds like quite the expert on that subject.