Can't select a location to store game data on secondary drive that is not under $HOME and not a Steam Library

Microsoft Flight Simulator asks you to select a location to store the vast bulk of the game files after you launch the game. This brings up the wine file explorer, and I cannot select my secondary hard drive, because it is not mounted under $HOME. The second drive (mounted at /home/second_drive) does not show up in the wine file explorer when using the Soldier SLR.