Selecting parts with large number of bodies as a remote mass in SW simulation

In my static simulation I have a typical situation similar to the example described in SW remote mass help topic: 2014 SOLIDWORKS Help - Remote Mass

A multipart, multibody assembly (chamber), which I want to treat as a remote mass, is supported by a frame, and I want to simulate the stresses in the frame. I am unable to convert the chamber to a single body using JOIN or COMBINE probably because some bodies are not touching.

Unfortunately assigning bodies to remote mass does not seem to support selecting multiple bodies at once, it has to be done one body at a time (see images). When the body count is in hundreds it is very time consuming. Is there a more efficient way?