Hey Magoo, I see more new stuff. Is that a diesel filling station?
I love my no grade, elevated, "warped oval" No concerns but weight for me. My 6.5lb GG1, and other heavy cast trains will bend my newer tubular 0-27 in no time. I didn't lay a support board under the track yet. But my little plastic docksides, "The General", and my switching diesels, love to pull small passenger consists around it. They can even be caught with a milk car, box car, gondola, or tanker delivery in tow behind the passenger cars on occasion. The weight your MTH track supports well by itself? I don't know. Test it out, watch for twisting or bowing, you may be fine. Your trestles will have to fit between your present tracks without being hit. Building a custom, "track directly over track" set of trestles might help, they can span a big gap for better placement. An oval leaves a bigger straight area for a platform, and the fig-8 will eat open area in the middle of the lower deck. To play without track purchase, you could rough-build in cardboard, hardboard, or wood for "testing the look". If it works out, you can keep building off it(if its not cardboard). Good looking homemade "cement" arch and pillar supports are easy to pull off with wood, and textured spray paint. Pillars use less space, and look very modern. I like I-beam spans and "boxes" best, over/under El style makes me drool. Firmly connect all the trestles to the layout! An elbow bump, or even derail into a loose support will twist things up real quick.
If you need another transformer, a low power transformer in conventional will keep it from ever becoming a missile. You are about to add a six inch drop to a possible high speed "big air jump". On multi-level, multi track layouts, train wrecks pile up fast, and furiously, as one train takes out another. Introducing a train from above, produces stuff worthy of Gomez Addams's sweet dreams.
