Wilderness Statblocks

[Prime Evil]

My preferred approach is not too different from your own - establish a baseline and then only record deviations from that baseline.

[Pursuivant]

If you've got access to it, you could modify the planetary statistics from GURPS Space to a smaller scale.

[Haseri]

It could work in terms of Regions, like the ones in Wildermyth, Worlds Without Number or this system from the Collaborative Gamer, as opposed to noting these stats for each hex.