The Nissan Path

I've taken the last few days to really delve into the lift situation. I read a lot of the posts in the Ultimate Lift Thread and saw a lot of love with the Rancho Quick lift, but didn't see much to do with the rear except the Airlift 1000 airbags, which I took a liking to since I plan to do some towing (RV yet to be purchased). With a little forum research and assistance from Amazon's confirmed fitment feature, I found the exact parts I needed to do a 4 corner lift/ level (front Rancho Quick Lift coilovers and rear struts with spring spacers, but never found anything about rear springs. I found some HD rear springs that will lift it 1.75" (0.75" over the MD springs), which would put it right about the same with the 2" rear strut/ spring spacer lift.
So these are my questions:
A) Does the spacer take the place of a replacement lifted spring?
B) Does the Airlift 1000 still work with a 1.75" higher spring?
C) Has anybody used the HD springs and is it preferred over the spacer?

I have used both the spring and spacer and can say just the hd spring will do the trick along side with airlift1000.
Old spring will sag eventually.