There are a lot of placed objects in-game that you can exploit into, and if they cover your hitbox, will act as a safe spot to mobs.
Exploiting into objects is as simple as either standing on it and then logging out and then in again. Or for objects like fences that you can't stand on, you can hold down run into it, and hit alt f4, log back in and you should be inside it, at the very edge. Sometimes just logging out right next to these objects can work.
Places this is useful are Ceres Labs (all those server looking things in the rooms which have the WoC disk dropping bots.
Oh and for safespot leveling, if you haven't already considered it, you should think about timing how long it takes to kill the mob, how long it takes to respawn, and then putting this in a macro and just leveling over night while you sleep. It's how I cap in a couple days