Probably not a problem in SLC, but I've reserved ski equipped vehicles at hertz airport locations at other ski destinations and have been denied a vehicle because they didn't stock ski equipped vehicles at that station. Of course, I would also be reprimanded because I booked and confirmed a "ski equipped" vehicle add-on through the hertz.com website and then had the audacity to assume that they would actually have any.

My guess that they'll force an upsell to the SUV rate if that's all they've got with ski racks, but it depends on the compassion of the customer service rep and you may get lucky.