I ride the SART in the evenings almost daily. I've been riding that trail since 1987. In those years I've seen drastic changes. Only in the last few years has it gotten to this point.
There have always been some overnight campers on it. One here - one there a mile later. The "off griders" stayed out of sight for the most part.
When the Huntington Beach Police did a sweep of the homeless along the first mile of the SART years ago they pulled all the mattresses out of the brush and old lawn chairs and just tons of junk - I became aware of just how much I was oblivious to. I knew there were some folks hanging out in there partying - can smell the smoke as I rode by, but no idea of how much stuff was hidden in those bushes.
Compared to the current situation of camps, that will take truck loads to clean up. The HBPD sweep was yard work.
I'd like to see the conditions reversed back to the bike trail and adjacent lands clear of tents and bike junkyards. I find the (homeless) people to be very friendly and understanding that any trouble they bring into the camp effects them all - they have never done anything I can say as aggressive towards me or anyone I know. That said, they are also somewhat wild - I've had them make 90 degree turns right in front of me and almost cause an accident - that happened 2 x - now I give them a very wide berth. BUT I have also had kitted up riders do the exact same thing - so...
As for safe riding - times and areas. I find from Warner south to the beach is the safest section any time of the day or night. When I do ride through the section north of Harbor Blvd. to Katella I usually go while it is light. The few times I've come home after dark through that area - people are wandering the trail in the dark. I've had several close calls with dark clothed pedestrians only because I couldn't see them and they were dead center on the trail.
My favorite encounter was the naked girl sitting center on the trail in the dark - I didn't know what to do???
The immigrant families with the toddlers playing in the roadway - trail - was a first this spring... They looked at me like - WAT?? when I suggested they don't let the babies play in the road.
I really don't believe that the homeless will rob you - but - I make it a policy not to leave my stuff unattended when strangers are about.
Some of the kindest folks I know have fallen on hard times. I have gotten to the point that I just live and let live. OH YEAH - I also carry a small pepper spray if what I believe isn't what reality provides.