On a hunch, I just successfully opened that BGL in Arno's ModelConverterX ("MCX") without having to decompile it.
You might wish to do the same, then export it as a *.3DS file to be edited and re-textured in GMAX for later export via the FS SDK.
Alternatively you could export it as a *.3DS or *.OBJ file and convert it to a *.DAE with another utility.
The *.DAE could then be edited and re-textured in Sketchup, for later export as a *.DAE back into MCX.
After re-opened in MCX, the "finished" *.DAE could then be exported from MCX in various 'non-legacy' FS9 and FSX formats, and/or put into an FS scenery object library for XML placement with your choice of object placement utility.