For what it's worth, my brother had portable raised track that he could assemble or disassemble at will. (Well with some effort naturally.) The track would run around his back yard, behind the garage and workshop, pool then down the far side fence.
Sorry, no photos to assist you but the construction was basically cross braced steel trestles in manageable lengths, bolted together with (for want of better term) fish plates and leveled as needed with various hardwood, steel scrap strips. His Locos were a Britannia and a V'Line (Victoria, Australia) "D" class. I think 3 1/2" gauge.
Something for you to think about anyway.
Edit, Now I think more about it, perhaps 5" can't recall