You must be 100% disabled. Here is an article from the US Military Campgrounds and RV Parks website that covers the eligibility:
News and Articles
MSgt, USAF Retired
Ed and Sharon
2010 Wildcat 28RKBS
2011 Ford F-250 XLT, 6.7L PSD
Ride-Rite Airbags and Airlift wireless remote compressor...nice!
I thought I was wrong once, but I was wrong!