Here is the start of the planning/building process - the tank is still in the box. The small side is going to be the water part, the larger side is going to be the land side. I'm going to use an aquarium safe epoxy to hold the rocks together, and then fill the empty spaces with Great Stuff Pond. The Great Stuff is also going to be used to hold the rocks to the bottom and sides, and for making a "stream" across the land.
This should give the salamander lots of space for digging and walking around. My husband is going to bring me a part of a log (either birch or poplar) which we will then hollow out so the salamander can have something natural to hide in/under.