Not a serious problem: Europeans already invented extra-narrow tractors for vineyards. You'd be amazed how much machinery they can drive between rows of plants that appear to be tightly packed. Or you can install the panels on tall stilts and drive under.
If you completely ignore repairing and paying for the automation you hypothetically could build a farm where the solar panels were on arms that would pull them out of the way of the tractors/combines or whatever.
I wonder if the weight of solar panels would prevent them being mounted on a wheeled device like the rolling irrigation systems used on many farms? Those are pretty robust and don't break frequently or require much maintenance; in the case of solar panels, they wouldn't even need to move frequently (so no need for permanent motors on them; you could just hook them to tractors or trucks and tow them out of the way). Though, there would need to be a lot more of them, and moving a bunch of them for harvest time or other stuff that required them out of the way would take a lot of time.
