@AmFlyer Sounds like a valid point on the slope of the ceiling. Maybe I can do a helix closer to the short wall and another at the tall wall. They'd overlap by about a foot in the middle based on the 6' you guys have mentioned so I guess if there's enough clearance for the train to pass under the second helix while it's at the top of the first one that might work?
Maybe 2 turns on each? Seems like that might get me a little over 2' and I can pick up a little more with an slight incline between the helixes across the 10' walls.
Thanks I really appreciate the knowledge and all the help from everyone!