You should be fine. The PA2Us are rated at 2amps continuous or around 4 amps peak and the AQ5 is rated at about 6 amps with EVERYTHING enabled. 18GA copper wire should be good for 16-18 continuous amps over the distance in a typical chassis, peak you could probably pull 24amps for a short period of time....

3 x PA2U = 6amps continuous or 12 amps Peak
1 x AQ5 = 6amps fully loaded (maybe more peak)

so you are looking at 12amps continuous and a peak of maybe 20. I think you should be fine.