Amnesia The Dark Descent: I need help with the level editor Thread

First of all, I'm working on a recreation of the mansion from Resident Evil 1 (a mix of the original game and the remake).

My first problem is that I can't find decent documentation on how to make a working skybox. I made one but it shows up completely stretched and glitchy.

My second problem right now is that the game crashes when loading the map I'm working on. I suspect that it's just too large now for the game to load it, because otherwise, the game runs just fine. I'm working on a side project as well, and by now it's a very small map by comparison, so the game runs that one just fine too.

I don't know how to troubleshoot this and since there don't seem to be any HPL2-dedicated forums out there, I just don't know where to turn to for help... so I'm posting here and hoping someone experienced with this level editor can help me out.