Yikes, that would be a tough nut to crack. It's hard enough to eat consistently low GI at home.
I've identified a handful of fast food options that work for me when I'm on the road and decide to eat out. Chopped Leaf has some respectable salads that I default to whenever possible. Worst case scenario, Subway works if -- and only -- if -- I make it a custom salad and do not partake of any bread. Obviously, Subways are everywhere. I don't enjoy this much but it works when it has to.
Most "real" restaurants can serve you up a tasty chunk of meat and some veggies easily enough if one has the discipline to stay away from potatoes, breads, pasta, rice, etc.
As for road snacks, I lean on peanuts, almonds, cheese, protein shakes, albacore tuna, black beans etc. These things are fairly portable. My wife makes a killer, low glycemic index chili that I really enjoy if I have access to microwave. I'm diligent about taking vitamin supplements when I'm unable to work vegetables into the mix practically.
In many ways, what dietary success I have achieved has been a product of my coming to grips with the fact that, for me as a T2D, food needs to be treated primarily as fuel, not comfort or recreation. And yeah, that does suck. But it sucks less than being unhealthy.
Were I your husband, I would seriously consider another line of work that would involve less time spent sitting and more time in close proximity to your refrigerator. That said, I recognize that changing careers is a pretty big ask for a family man so you'll get no judgement from me on that front.