I am mitigating that concern by mowing in reverse for the time being as well as using the bucket on the front of the tractor to knock targets down if mowing in forward motion.
Actually, the fan isn't nearly at risk as much as the hydraulic oil filter. The fan is covered from beneath and the mower lift linkage runs right in front of it as well so it's not that big of a problem. The oil filter, however, is completely exposed.
I'm very disappointed in JD for this design. I will entertain no excuse. Even the sales guy at my local dealership could only shrug with perplexity when I asked him about it. He's a good guy and I really appreciate his honesty but it sure doesn't help resolve the problem. When I have some free time, I'm going to fashion something up for it. Until then, I'll just continue to be very careful where I go.