Only upgrade on the cooling system is the upgraded water pump design. And well, maybe the FRRP PI intake. No radiator cap but overflow tank works fine.
After researching this further, this is not really an uncommon or unknown problem. I feel dumb for not discovering this 20yrs ago but, Ford knew quite well about the issue. Not so much with blowing the hose (probably my saving grace) as in prematurely destroying the heater core. There are two flow restrictors available. XR3Z18599AA came stock on 96-04 Mustangs, 2003 Cobra, and all police cars Ford made. The other appears to be discontinued from Ford but re-created and available from a few vendors (E7VY-18358). Both fit into the heater core inlet (3/4"), restrict the flow down to 1/4", and fit 1979-2004 Mustangs. Quite a decrease in size! However...the E7VY-18358 is basically just plastic, while the other is plastic with a rubber washer inside that acts as the main restrictor. Looks like a smaller version of the rubber washer you put on garden hoses. I imagine there was a reason they altered the design to be a bit more dynamic with this rubber section...
I haven't installed it the restrictor yet but, I am happy to think this might keep me from replacing another heater core. #3 or #4 in 20yrs. Geez...
Still interested in hearing if anyone has done any other mods/tweaks to thwart the pressures in that section. Or have installed one of the restrictors with results.