If you're not above a bit of "justifiable cheesing," you can exploit the low poly density. By clipping a portal exit side into the rock, you can create a small hidden base or fighting platform.

This seems like a "low-down dirty speed-runner trick." ;) But the engine limitation you exploit is the same as the limitation that prevents you from using such a rock as you would irl. Hence, it's "justifiable cheese," imho.

I haven't used it after playing with it in my first run: it breaks the fantasy, for me. However, lately I've been imagining the world our characters find themselves on is a training simulation based on the original Valheim.

This would make a lot of things possible, like integrating options / difficulty selection inside the game as "training choices," say. At some point early in the game, Hugin shows up and admits that Valheim is not just a testing and proving ground, but a training ground as well. You can choose whether you want to aim for "Combat Engineer" or "Berserker," etc. and this turns various options on and off.

By doing that, immersion is not broken. We stay inside the fantasy instead of going out-of-fantasy to some computer-sciencey options screen (however disguised with graphics)

So, back to these rocks: A Viking with Kirk's attitude would absolutely exploit justifiable cheese.