You can raise track sections and and create uneven terrain by carving 1" or 2" foam into small up and down ramps. In addition, Woodland Scenics makes foam risers that do the same thing, although I'm not sure you need or even have enough room to do that.
If you can start your graduated trestles back closer to the switch, you may be able to gain enough height to install a bridge along the long side wall. The Lionel bridge with flasher (6-12772) and rock piers would be a good choice and add lot of visual interest if you can fit it in. You might need to swap the trestles from the Lionel set to the MTH set.
