“If the rule is 1 aircraft per thousand tons, how did the USN converted Essex CVs carry 60 F-8/A-7/A-4/A-3/S-2 aircraft on 42,000 tons max displacement?”

I would think that can be explained by the different ‘footprint’ of these aircraft:

F18E L=18.32 M W=13.62 M (wings folded: 9.32 m)
F-8 L=16.61 M W=10.87 M
A-7 L=14.60 M W=11.80 M (wings folded: 7.24 m)
A-4 L=12.29 M W= 8.38 M (non folding wing)
A-3 L=23.27 M W=22.1 M

E2C L = 17.60 m, W=24.56 m (wings folded: 8.94 m)
S-2 L = 13.26 m, W=22.13 m