I often do that and it works for me. I do two proper fast days on Monday and either Thurs or Fri but on the inbetween days I often go from the previous nights supper at around 10pm through to my evening meal with just fluids. OK, so it sounds not unlike an extra fast day, but I don't cut back to 500C or give any great thought to what I have on those days. I don't beat myself up either if I get to about 4pm and decide I need something more solid than a bouillon!
I know that the theory behind the 8 hour eating window and not being able to overeat in that time could be blown out of the water quite easily by most of us on here when we first started, but once you have a few fasts behind you it does seem to work as you get so you don't like that bloated and overfull feeling so you get the relaxation of eating what you fancy but you do tend to eat much more moderately.
Anyway, give it a shot. We're in it for the long haul not a quick fix. You can always return to the drawing board if it doesn't do it for you.