My usual approach is to simply delete all parts except one. I usually have two models, one for baking/uv-mapping and one for final preview. The "baking" model, in this case, would have only one antenna and one side of the walls. Once that is unwrapped, I would duplicate it and copy-paste-mirror-rotate in the missing parts for the "final" model
Edit: btw, if you want to open your file in an older blender version, choose save as and check the "legacy mesh format" option
Models by Michael
Re: Models by Michael
-insert deep philosophical statement here-