Hi again!
I made this mod that uses the built-in map generation module to make an infinite dungeon (multi-levels inspired by Simon-v's multi-level module, but perhaps less elegant). Also, it is set up to allow you to specify special levels like in real DoomRL. Included is Hell's Arena on level 1. The multi-level bit may be dodgy, but I think the random level stuff should work well (potentially perfectly).
The player placement issue is resolved by replacing Generator.place_player (and a few other problematic doodads) with a more single-level friendly version.
That said, this mod isn't really fun (or it's not any more fun than playing Doom RL on itytd), but it's a proof of concept that anyone is welcome to use for their own devious purposes. Since special levels are included in the sandbox, it would be very easy to make this a very close copy of DoomRL. Hence, we could make our own challenges or new special levels :)