Aircraft are still showing exoskeletons as a valid grid item.

Likewise, could the Better Cargo Planes have a larger grid, as they are nearly useless in combat, but should be able to make use of personal roboports and such.

Hm, if you are seeing the exoskeletons appearing for all aircraft, then you may have another mod that is conflicting with this one. If it was only the cargo planes that still showed the exoskeletons as a valid equipment, then that would be because I originally missed adding equipment grids to the cargo plane (and didn't have compatibility set up for Better Cargo Planes).

I think it's also important to note whether or not you are using Krastorio 2, as their equipment modifications have the biggest impact on how this mod functions.

However, after adding compatibility to Better Cargo Planes, in vanilla, all aircraft have roboport available to them, and do not have exoskeletons as valid equipment. The cargo plane grid sizes go from 8x8 to 10x8 to 13x12 (matching the size of the flying fortress grid); this should be plenty large enough, and dwarfs the vehicle equipment grids I had set up for base game vehicles, as well as the other aircraft.

With Krastorio 2 enabled, the cargo planes are the only ones with roboports available to them, including the Kras2 vehicle-exclusive roboport (Kras2 specifically disables roboports in the other aircraft, I think), and of course, exoskeletons are not considered valid equipment (it also seems that Kras2 and Better Cargo Planes alone don't entirely support each other by themselves, as Kras2 disables exoskeleton legs in the other aircraft, but not in the cargo planes, so this makes for a good patch mod between the two). The cargo plane grid sizes go from 8x8, to 10x8, to 13x12 (which is actually MUCH larger than the Kras2 version of the flying fortress grid). This should be more than large enough, I think?

Compatibility updates incorporated as of v1.0.11

I don't have K2 installed, but when I hovered over the exoskeleton it said that all aircraft were valid places to use it.

I haven't checked since you updated though.

https://i.imgur.com/me6EFhF.png
https://i.imgur.com/fEWh8gq.png
https://i.imgur.com/v2bFQPt.png
https://i.imgur.com/RTxg1nB.png

So I made a save with just Aircraft mod, Better Cargo Planes, and Sensible Vehicle Equipment Grids. Exoskeleton still shows up as being allowed in the grids of all the aircraft from the Aircraft mod. I'm thinking it's something in there that's messing with the setup you're going for. The first level of cargo plane also shows an 8x4 instead of an 8x8 grid. The other cargo planes show the appropriate grid size.

Hm, judging by the screenshots, my mod isn't actually having any effect on any of the cargo planes. I get the feeling it might not be affecting the aircraft either. In the 4th screenshot, you can see the mods that are affecting the Cargo Plane being Aircraft and Better Cargo Planes (since it was made by the Aircraft mod, and then modified by Better Cargo Planes). My mod isn't listed among those.

The only reason I can see for this, is that maybe you have the "Non-combat mode" setting enabled, since that's the only other check I have in the code.... Oh, I see the issue. Since I originally only had the other aircraft, I had to include a check for the "non-combat mode", to ensure I wasn't trying to modify an item that didn't exist, and I just lumped in the cargo planes to the same area of code. I've also noticed that non-combat mode just prevents the crafting of those aircraft; so they actually DO still exist in the code, meaning that I don't need to even check for this setting in the first place...

But anyways, simple fix; should be working as of v1.0.12

Looks like it works now! Awesome!