If you move outside of the OMCs, motorcycle "gangs" (clubs/associations) have a very interesting smattering of personnel. Oddly enough, you've got a very heavy leaning of tech industry people in these. You could have more than just traditional heists right after SHTF... some of these people not only installed security systems, but designed and implemented the entire networks behind them... and hell, may even have access to high level DoD systems due to their "day job!"
The local BACA (
Bikers Against Child Abuse check them out, awesome organization) chapter where I just moved away from had some very colourful characters. I worked with one of their members, he was had been a firefighter and police officer for 20 years and got his pension. He worked IT to pay for his hobby ranch with milking goats, horses, and a few exotic animals. His wife and kids were in the tech industry, several of the in-laws and even a grand-kid were part of the MC he was in. All were avid shooters, I'm positive some were military.
Think about that. You've got a police veteran with knowledge of emergency procedures both physical and electronic, as well as enough animal husbandry for subsistence. He has a literal clan (if small) who can be counted on for technical and agricultural support, and all capable of shooting--some with real combat experience. And that's just
one member! "Everybody has a story," after all.
External to himself he's got a network of contacts quite well versed in instantaneous rapid reaction. Some of them were reformed criminals, others were just "geeks with bikes" looking to improve their self-image, an some were (allegedly) active criminals who could simply agree to a truce for the sake of BACA's mission.
They have constant meets for riding, shooting, organizational or even purely social reasons. In total the chapter had probably 50 Members and Associates.
Now, when SHTF, who do you think these people are going to call? It ain't AAA, that's for sure.
If you want an interesting group for this kind of thing, but are looking for something a little more "White Knight" than an out-and-out criminal gang... BACA could be just what you're looking for.