I feel pretty safe with all this but it still honestly scares the crap out of me riding at 30+mph with cars.

30mph is pretty cooking. I only get up to those speeds when I’m riding downhill (thanks 18% grades). If you can, especially when not on the road with cars, try slowing down a bit. A 20mph collision (or allision) is much safer than at 30.

At 30mph speeds, definitely look at motorcycle gear. Illuminate your bike (good rear and front lights). Consider a mirror on your handle bars or helmet. Maybe take some online courses on how to ride a motorbike and translate it to your fat bike.

FortNine did a nice little short about this space, though mostly so folks stop pestering motorcyclists about the danger on the roads. The reality is the cars are the danger for both motorized bikes and pedal bikes. Defensive techniques are your only option.