I have never heard of a good source of statistics available to the public on crimes in the WMNF. There are multiple overlapping jurisdictions and it usually it takes a string of property crimes for the various agencies to finally decide who is going to expend resources to deal with it. The loss of local news coverage is also an issue. Many of the local subscription/paid circulation papers are gone with a few advertising based freebies left. They do have news staff but the staff are mostly assigned to local interest events that draw "eyeballs" to the paper. Unless its a major event with a chance for regional or national interest its doesn't get in the paper. The primary advertisers are tourist businesses and they do not want to draw attention to things like car break ins and thefts from tourists aren't local news and doesn't get reported. There is obviously social media but its highly variable if a report makes it into circulation.
I guess if there were a lot of break ins a site like TrailsNH or Jeremy's site could add a category for car break ins but my perception is its not bad enough currently to warrant it.
My general perception is that car thefts are way down compared to its peak but there are still thefts of opportunity. If someone is out to steal things, its smash and grab (assuming the doors are even locked), the goal is to get cash and easy to get rid of valuables quickly. I am quite surprised that the opioid epidemic didnt bring in a wave of property theft although there was a couple that were busted last year working the popular lots on the Kanc that were alleged to be supporting a habit of some sort. In general I see a lot less broken window glass in parking lots then 20 years ago (but I still see it on occasion).
My perception is that there is some attempt to weed out out of the area transients that have on occasion been the source of car breakins. In the past I think the local communities basically pushed them out of the local towns boundaries onto back roads and onto the national forest lands many of which are unorganized territories. Coos and Grafton counties both have sheriffs departments but they tend to act as support to the courts and civil matters and avoid actual policing. Talk to anyone who has had their car broken into in Success or in the national forest and the big challenge is finding an agency to respond. The expansion of 911 seems to have put in place better coordination between the agencies. There was one large case tied with a transient that lived out of his car in the Great Gulf area that worked cars along Rt 16 and Dolly Copp road and a much larger problem with a transient that lived on a mix private and public lands off the end of Rocky Branch road and the end of Town Hall road (Slippery Brook and East Branch fire roads) in Bartlett that worked lots in a fairly wide area of the National Forest. Some may consider this harassing the homeless but it seems to have worked to reduce property crimes at hiker lots.
A general observation is that the unorganized sites with the worst reps tend to be on the south end of the old Cherry Mountain Road, there are some larger sites that have tended to get a party crowd. The sites along the North Twin, Gale River and Garfield roads seem to have a better rep but its low priority for the WMNF so the sites can and do build up trash and the surrounding woods are always littered with toilet paper. I have also seen spots where campers have run a hose into the woods and dumped their waste tanks. There are few unofficial spots on the north end of Jefferson Notch road that seem to be quiet although in recent years there have been a few new sites opened up off the paved section near the three bridges. These are not signed as camping areas but inappropriate spots are signed no camping on the southern end. There is also the hidden site off the road where a snowmobile trail heads over to Cherry Mountain road. The other organized boondocking area is on RT 113 north of Evan Notch and I notice the road to it has been signed consistently with a warning about the maximum number of days a vehicle can be parked. Head over to the far eastern WMNF off of RT 113 and there is little enforcement and lots of places to park without being bothered. They are quite a drive from southern New England and do not get much use. Note most but not all roads in the WMNF are covered by the 1/4 miles RUA rules that restrict camping to designated spots just pulling off the road is not acceptable. Appalachia abuts state owned land and on occasion folks will camp in the strip of land between the low and the railroad track. Its a noisy spot with traffic on RT2, there are several state troopers who live in the Berlin Gorham area and the barracks is in Twin Mtn so they drive by the lot and also drive through it on their way by.
This year I am seeing far more camper vans with out of state plates with the windows blacked out parking overnight in hiker lots, I expect at some point there may be crackdown as the lots get busier.