100% of the time I've put this to the test I get the same result: to within a very large range of calories and carbs, calories consumed during the day affect my fasting bg levels the next morning far more than carbs.
Last year I did all sorts of experiments trying to work out how my body worked and this particular result was always dependable: If I ate an amount of calories that was definitely 'above maintenance', even on low carbs, my fasting glucose would rise. If I ate an amount of calories that was definitely 'below maintenance', even on high carbs, my fasting glucose lowered.
I never pushed the tests to the extreme, e.g. zero carbs, so I'm not sure what the boundaries are, but they are pretty huge.
I verified exactly the same phenomenon again quite recently. Over the last few months I must have been eating more than maintenance calories as my weight has increased. So recently I double-checked my diet one day and sure enough the carbs were 20g but the calories were high. I really needed to solve the problem as, on the surface, my lifestyle seems very active and healthy recently, but weight and fbg is heading the wrong direction. So I did the same experiment again: I switched from 20g carbs and a lot of calories to a day of 270g carbs and much less than maintenance calories. The next morning my fbg had dropped to a lower level than it had been for a while.
I'm not under the illusion that means it's safe for me to eat big carbs - the individual spikes after eating will have been huge and are likely to make insulin resistance worse. But for me, over a period of 24 hours, energy input is a reliable predictor of blood glucose in the morning, and carbs are not.
It's not exactly a revelation - the various Newcastle studies show very clearly that if you restrict calories, even on quite high carbs, you can expect fasting glucose to lower. The upshot for me is that I need to count calories, especially if I am doing a lot of exercise and increasing my appetite.