Hill Country SNA is an option, as well -- there are a couple different primitive campsite areas that require a hike-in and you can take however roundabout a route you want to get to them if the shortest distance is too non-backpacking like (eg. makes you feel like you're just hiking with too much stuff on your back.

)
I haven't backpacked at HCSNA yet, but I've hiked and camped there many times.