Don has a very good point & I could see a fistfight or two breaking out over it. Maybe you need to space the bundles 1 bundle diameter apart.
I feel I correctly answered your question about space in the ordinary sense, but I didn't do so in the context of your question.
In any case, since you are dealing with #10 conductors, it appears that 310.15(B)(2)(a) would require a derating to 45%. Therefore, #10 would be OK since its final ampacity is more than 125% of the 14 amps the motor draws.
It would be interesting to apply Exception 5 to 310.15(B)(2)(a) by using #12 & supporting on bridle rings instead of cable tray. What do you think?
Few things are harder to put up with than the annoyance of a good example.