HO Layout in a small room

In our new house we have a small storage room that I'm planning to convert to my train room (and also run the server computers there). The room is 167x283cm. Enough space to set up a new layout of our Maerklin HO trains, but it's all very, very tight. I discovered a free track layout tool XTrkCad from sillub.com that works on Linux (and Windows, too). It's definitely dated by today's standards and compared to currnent tools available for Windows, but gets basic planning job done.

The theme I'd like to build is a small station at a double-track mainline with some side-tracks and engine maintenance facilities and a single track spur line that goes steep into the mountains. At the end of that line is a small rural station with a little freight and passenger traffic. I also definitely want a hidden storage area for trains. To make things a bit more interesting I figured I set the station at a 15% angle diagonally accross the available space.

The problems start with the fact that a 180 degree curve double-track is 105cm wide, so that leaves at most 55 cm on the side of the layout for the operator that does need to fit into the room as well.
In order to avoid too steep grades, I don't want to go above 1:40 on the main line (i.e.4 cm elevation gain on 1 m of track). That means my grades need to be at least 250cm long to get 10-11cm clearance. That is almost the full length of the room. Taken together it became clear very quickly that I need to pay very close attention to grades and clearances along the track, as well as use every centimeter of track I can get for elevation gain. This is going to be one heck of a mountainous layout.

The railroad builders of the railroads accross the Alps or the Sierra Nevada must have felt similarly...