This is likely to be a long post.
When I first started Atkins (early 2003 or late 2002), I was an OTR trucker. I managed Atkins very well (plus exercise) until I came off the road to go to graduate school. I lost 50ish pounds while trucking around the USA (and Canada occasionally). Even after I stopped exercising, I continued losing the weight.
First the exercise: I walked around the truck stop parking lots, then started jogging (time it so it's not busy and the lot is mostly full and keep a sharp eye out) around the lot. Then when I decided it was too muggy to do that, I got a mini stair stepper for the sleeper (a la Denise Austin's version). I also jumped rope next to the truck.
Now for food: I stuck to the basics and did not have much variety. I cooked and ate in my truck. My no-cook standbys were meats mixed with mayo and cheese. Rotisserie chicken from Wal-Mart (many allow you to park there but more and more don't so look for them close to truck stops, i.e., Oak Grove, MO - park at the truck stop and walk over) and other grocery stores. This is easier if you are on US Highways (i.e., US 54 across KS) instead of the interstates but doable either way. I also ate a lot of canned tuna (foil pouches were easier because the don't require draining. I assume you have a cooler/fridge so mayo, mustard, pickles, hard-boiled eggs, cheese, deli meats (probably not low carb but the Petro at Milton, PA on I80 has wonderful sweet bologna and Lebanon bologna), celery, cucumber, spinach, etc. should not present a problem. Eggs and steak at the truck stops are always a good bet - especially if you have points available for free meals.
As for cooking in the truck: this depends on your comfort level. The lunchbox cookers (Burton's Stove-to-Go) are probably still around and safe. They are like slow cookers but you'll need turkey bags to cook and make cleanup a snap. I had also had a butane burner stove - much quicker at cooking. That's where your comfort level comes in - carrying butane in the sleeper compartment. But I used it to fry eggs, bacon, chicken, etc. It saved time.
So here's a list of foods for ease:
*Rotisserie chicken
*Cheese - shredded or cubed for adding to cut up chicken; string cheese (watch the expiration dates on these but can be found at truck stops)
*Pre-cooked hard boiled eggs (Petro and Pilot carry these in packets, otherwise, Wal-Mart)
*Mayo
*Mustard
*Pickles
*Olives
*Cucumber
*Celery
*Spinach (lettuce)
*Tuna (foil pouches or cans)
*Salmon (foil pouches or cans)
*Canned chicken/ham
*Splenda packets
I realize it's a limited list. However, look at what you ate on the road when you were high carbing it. How varied was that menu? I'd bet not all that varied. At least mine wasn't.
I also cut out caffeine while on the road. I didn't drink coffee but I drank a LOT of soda. I usually stopped at Flying J's for caffeine-free diet coke. I used my 32 oz mug and started mixing 3/4 reg diet coke and 1/4 caffeine-free diet coke. Eventually, after about 2 weeks, I'd decreased the amount of regular diet coke to zero and was drinking caffeine -free exclusively. Then I cut out the soda entirely. I found I didn't need the caffeine while low-carbing. I had energy to spare.
Low-carbing while trucking is not the most simple thing. It takes planning - just like low carbing while not trucking. I found it difficult at times to not resent that I couldn't just stop at Subway or Arby's or McD's. And, because I ate in the truck 8/10 meals, I was cut off from the other truckers and was a bit anti-social as a result. But the advantages - decreased weight, better skin, better hair, better mood, better energy and being able to drive up to, through and then after sundown without getting sleepy, made the difficulties worth it.
It is doable. I'm happy to answer any questions I can or give pointers. Just ask. Good luck!