I don't think high fat and SOME carbs is necessarily counter-productive. I've been doing c. 100-113 total carbs and always 20 or fewer "carby" carbs (grains, potatoes etc.) per meal. And this seems to work for me. I've been losing weight. The thing you have to make sure to do is keep your blood sugar low (and therefore your insulin low).

But you have to eat something the morning after, right? So high fat and/or protein is pretty much your only choice, right? Fat is protein-sparing, so I say do some of both and fill up on fat to spare protein.

As for eating out at restaurants, I think Asian places are generally pretty good because most of them usually give you the major carb source (usually rice) separate from the rest of it (tofu, vegetables, fats etc.). So you can just fill up on the tofu/vegetables and eat as much or as little of the rice as you want. And many places will give you brown rice for no extra charge, which will help in keeping it low-GI. Mexican would be a little bit tough. I would probably just get a side order of beans and/or guac and maybe eat a few tortilla chips. I'm having trouble coming up with any other option that wouldn't be pretty carby. Maybe vegetable fajitas (hopefully with beans), but just skip all or most of the tortilla shells. Indian is hit or miss. If they have a good vegetarian spread with dal, chana masala or some other legume-dense option, it can probably work fairly well, but it might not feel all that satisfying.

These are situations where having a good protein powder can be a huge boon. Just fill up on plenty of fat, try to maximize protein and minimize carbs, then drink some protein powder when you get to your car, office, hotel or whatever.