Steve it sounds like your going to lay your own track, I would pick a median point between the two widths, you can always cut a tiny sliver out of an axle and CA glue it back. There actually plenty of play with the wheels and track to accomodate slightly different widths. If you have any issues let Wayne or me know, we'll find a way. But please make your own track, its so easy ad looks cool.
For my last dio, I layed a bed or corkboard then cut some basswood the size of the Trumpeter ties (thats a good go to size), glued them using spacers like laying tile between them. I cut out the cleats from the provided Trumpeter tracks and CA glued them to the ties and again used Trumpeters rails. Woodland Scenic makes a nice ballast in different sizes and colors, just pick one. Once the ballast is in place I sprayed on Woodlands spray adhesive that locked it in. It sounds way more complicated than what it is. I just thought I'd add this in case anybody is checking the site, sothey can find a way to make their own tracks.
Terry