Just to elaborate on my earlier post, I have taken a photo of the rail joiners that I referred to earlier. I emphasise that these are FUNCTIONAL fishplates not the easily-obtained ABS or brass COSMETIC offerings from C&L and Exactoscale. They fit superbly and are inconspicuous too.
A tad too long so, fit to one rail, cut to length with side-cutters, push further onto the rail to re-open slot, job done!
Dave