Interesting, thanks pal.
Unfortunate that a bass F has an ideal gauge of around .018-.020, as this is precisely the critical and problematic transition point from wound to plain: at around these gauges, a wound string would have a very thin core barely able to take the tension ... however a plain string, being a solid rod, is inflexible and has a somewhat dull inharmonic tone. I don't like to use plains thicker than .016.
So now when i design a tuning i work outwards from this point, starting with the optimum wound-to-plain pair of gauges and then adding strings above and below. I always use the thinnest practical wound available to me, which results in the thinnest plain string adjacent to it. I also drop the tension from wound to plain to mellow the tone of the plain for a better tone blend, also a thinner plain is more flexible for a better tone.
Some examples from my past:
Fifths Conklin .022w, .013p
Fifths D'Addario.025w, .014p
350 cent neutral thirds D'Addario .025w, .016p
Interesting and lucky then that many standard guitar sets go from .024w to .016p.