Would it be possible to change up the way the tiers work? What I envision is having the following.

Tier 1 (nivex1)
Additional bases nivex1.1, nivex1.2, nivex1.3
Tier 2 (nivex2)
Additional bases nivex 2.1, nivex2.2, nivex2.3

So on an so forth. This would allow you to have different base types in each of the tiers. Such as I don't want to use a small 2x3 base from my easy tier in my higher level tiers.

You would be able to have 3-4 different base layouts in each tier of difficulty.

the plugin already functions this way. easy medium and hard tiers/difficulty.

"Difficulty (0 = easy, 1 = medium, 2 = hard)": 0,​

Yes but it uses the same nivex 4,5,6 in all three difficulty levels. Only 1,2,3 are will be different base structures at each difficulty.

If nivex 4 is a simple 2X3 layout it would be used on easy, medium, and hard.

If I have custom loot tables for each difficulty level that 2x3 base at hard level is going to have the same loot as nivex 3 which I envision as being more difficult to raid than 4,5,6 in size and material used.

I found a work around in an earlier post from rekoo. Im not sure if it is breaking anything but it seems to work. I can have 4 different bases at each of the difficulties.

https://umod.org/community/raidable-bases/20847-ready-to-use-configuration-with-bases?page=1#post-1