OK, let's see what people can agree on. There are two hex numbering systems I know about, and this is the more usual one:
https://i.stack.imgur.com/GSVWK.png
(The other one has the first two digits as here, but the last two assigned along the diagonal hex rows. It's harder to do calculations on that.)
Because the
Triplanetary map is conventionally aligned with the hex points up/down, I propose that the bottom left hex should be 0101; the hex to the right of it 0201; the hex above them both 0102; and so on.
By my reckoning this puts Venus at 1009, Mercury at 1810, and Sol at 1613. If other people agree with me, that's a good start.
sgbeal, it seems to me there's an opportunity here for your SVG map kit…