Air Ride for the Rear?

[chevy one]

Working on my 67 2WD, LWB with coils,wanting to know what is the easyist and cost efective way to bag the rear. I am lowering the front 2" with drop springs, and want to lower the rear (appox) 3". I still want to be able to tow a 20' travel trailer from time to time. Found these on eBay:

ARNOTT AIR SPRINGS 100 MM STRAIGHT SLEEVE AIR SPRINGS SERIES, PAIR 14" MAXIMUM EXTENSION! THESE ARE CUSTOM AIR SPRINGS DESIGNED FOR VARIOUS APPLICATIONS. PART# 10014VR.
SPECIFICATIONS:
Ride height 10" Max inflated diameter 5.7"
Minimum compressed height 6" Full extension 14" 1/4" NPT air inlet 1500 lbs. @ 100 PSI.

I don't know if the 1500 lb will be enough for towing? Any advice would be great.
CO