With all the trouble we go through setting clocks and worrying about batteries, it's amazing that no one has suggested a cart-based or internal mod atomic clock. Home built kits with RS-232 out have been around since the early eighties from Heathkit. WWVB has been around since July 5th, 1963. All we really need is a way to present the clock as an R-Time 8 would, but I'm too out of practice to do anything productive in this department. Does this sound like a good idea?
Super small WWVB receiver and antenna available here