Transition over module gaps (cross posted from tips & tricks

[Sumpter250]

Option 2
My concern with option 2 is how to ballast the transition piece so it blends in with the rest of the track. As it needs to be removable and the fishplates/track joiners need to be easily moved after a year. Has anyone had any experience with this?
I appreciate any advice.
Kind regards, Steve

I have used thin styrene sheet, glued to the bottom of the transition pieces, to be the base for ballast. Yeah, you have to be a little careful installing / handling them, but they carry the ballast right up to the ends of the module's track.
In one place on my "new module set" the module boundaries are crossed by removable bridges. My lower in-module loop, by a rolling lift bridge, and the two "required" mainline tracks, by a two track through girder bridge ( two Atlas single track bridges, kit-bashed, side by side ) In this photo you can see the module boundary, and both of the bridges:
   
Unfortunately I do not have any close up photos of the ballasted pieces, in place, and the modules are in their trailer, waiting to go to Trainfest, in Milwaukee, on Friday 11/13/15.