I am not speaking specifically to your unit... Most solar generators seem to have some tolerance. If you go over 60V, they simply will not operate.
60V refers to Voc, not Vmp.
Voltage is maximum at zero current. Voltage at zero current is not significantly affected by the mentioned distance. In reality, a tiny amount of current has to flow to take the voltage measurement, but the difference between the open circuit voltage at the panel vs. 40' away is probably smaller than the error in your voltmeter.
If you plan 62Voc and not 62Vmp, it's probably going to be fine. Voc is rated for CELL temperature of 25°C. Cells are almost always hotter than 25°C except in cold (freezing and lower) conditions.