We can construct a standard version of the Eudoxan model for Mercury. Keep in mind, however, that this is pure speculation. These are the considerations that should go into any reconstruction, even if not all of them become part of the actual model we use.
Invisibility occurs when the planet is 1/2 a zodiacal sign from the sun. The evidence for this principle is that this is the theory we find in Autolycus (about 3/4 century after Eudoxus).
Mercury is isodromic with the sun (has the same ecliptic period and stays with the sun) and so has a zodiacal period of 1 year, so that sphere 1 rotates about 366+ times east/west for 1 rotation of sphere 2 west/east.
Tbe synodic period is 110 days. Here it is indeterminable whether our source, Simplicius, intends sidereal or solar days. The difference will be insignificant in any case, i.e., less than one day.
Mercury has a retrograde motion of about 1/2 sign.
The invisibility period of Mercury for last evening appearance to first morning is about 20 days or more (if a phase is skipped).
The invisibility period of Mercury for last morning appearance to first evening 15 days or more (if a phase is skipped).
The maximum elongation of Mercury is small (should we take one sign or 2/3 sign).
Mercury changes its latitude by as much as 4.65 degrees from the ecliptic. How one might observe this is tricky, as one needs to measure this either off a fixed star whose position relative to the ecliptic is known or by knowing where the sun would set were it at the position that Mercury is now or by some other method appropriate to the world of Eudoxus.
Sometimes, Mercury does not appear at all on one side of the sun, i.e., a first morning follows after a longish period a last morning without evening appearance in between or a first evening follows after a longish period a last evening without morning appearances in between. An ancient astronomer might reasonably conclude that this presumably occurs because its elongation is sometimes too small for it to make an appearance. Besides its being true and a feature of Babylonian astronomy, Aristotle notes the phenomenon in the Meteorologica.
No version of Eudoxan models can account for the discrepancy between the two invisibility periods (not so profound in the case of Mercury), since the curve is essentially symmetric. Nor can any model account for the fact that Mercury sometimes appears and sometimes does not. At least, one would have to adjust the center of the hippopede, which would require more spheres. A 1/2 sign curve (15 degrees) will make Mercury rarely, if at all, visible. So 2/3 seems more reasonable, along with attributing the failures of appearances to other causes, such as atmospheric conditions.
Assume that the poles of spheres 2 and 3 are 2/3 sign (20 degrees) apart, i.e., that the angles between the equators are 2/3 sign. Hence, the loops are each 2/3 sign in length. The maximum latitude will be 5.18 degrees, but in the wrong part of the cycle. However, at least in the case of Mercury, this would not be noticable, since the planet would only be visible at the extremes of the curve.