My beginning of ZosoRailways

As far as I understood, MTL has a raised bed track too and looks very similar to Rokuhan (excepted for the space between sleepers, and only for the non-flex sections) ; Rokuhan makes straight track sections without ballast to be used on their bridges. And standard tracks without ballast are those made by Märklin and Atlas (and perhaps Peco, but it looks like Atlas).

When I began building my layout, in 2017, the Atlas track was "new" and unfortunately had no holes for nails, turnouts didn't yet exist. And the sleepers of Märklin broke very easily when I pushed in the nails. Si I used Rokuhan, fixed with small screws. But I had to raise all plattforms (for passengers and freight) to make up the addtional height (most via Evergreen or 3D-printed parts) ; so, if the building has no fixed ground plate (or if You can remove a part to allow the train to enter), You could use the same solution ; painted grey these additional parts would look like a concrete foundation ; and if You want You can even add stairs.

For example the attached pictures show such modifications ; the freight depot was kitbashed from two Faller kits, with a completely new built base, the length allowing 5 freight cars.