I spent quite some time looking, dear Dave! Fender 6 strings have thick ball ends (no one told me!) and they also have the manliest gauge: 025, 035, 045, 055, 075 and 095 (the gauges aren't an issue, the ballends are!). Unusable on the original EB-6 bar bridges, but if you used a Schaller six string roller bridge you might do fine even though I would imagine the thicker ballends sticking out from the guitar ballend size cavities. But beauty is only fin-deep as they say.
Small ballenders:
I have a couple of D'Addario XL155 Jerry Jones guitar/bass with small ballends string sets which I haven't used on any of my two EB-6s yet: 024, 034, 044, 056, 072 and 084.
And you can order from GHS a slightly thicker custom set for Fender VI with small ballends: DY26, DY36, DY46, DY56, DY74 and DY90. I have those with good results on both my EB-6s.
Then there is an Ernie Ball 6 String Baritone Slinky set: 13, 18, 30, 44, 56 and 72. I haven't used that yet, it's probably too thin for bass tuning, though you could always tune an EB-6 as a baritone (better for chording too), but if you used the 18 as your E/F and worked yourself down from there plus obtained an 82-85 small ballend string from EB as an extra for the low E, then it might just work.