There is a mod today (smurff) that with a few lines does, quote - "Stock and stockalike liquid fuel tanks (LFO, LF, Monoprop) have a fuel mass fraction of 87-89%; SMURFF increases this to 97% by reducing dry mass by 76%, putting them in line with real spacecraft fuel tanks"
This works very well for those who do not want to go full RO. It would be dead easy to implement a stock smurff-alike function that matched one's chosen stock scaling.