It is suggested that you have that vent space, not a requirement. Having air flow allows for a longer lifespan of the appliance. It is just wanting to get airflow into the base, I would opt for putting a vent in the base of the cabinet above the toe kick.

I am in the process of making an induction cooktop purchase decision, and was surprised to note the venting requirement when I reviewed the on-line installation manual. I found this posting as part of trying to make sense of the requirement. I like the creative idea from Sativa McGee Designs. However, unlike Sativa McGee Designs, my reading of the installation manual is not that having the vent space is a mere "suggestion." Rather, the directive is proceeded by a capitalized and bolded "IMPORTANT" and is grammatically written in the imperative as follows:

"IMPORTANT: For proper ventilation, provide a vent of 3/16” (5mm) under the countertop, in the front of the cabinet. The ventilation opening is to extend the full length of the cooktop cutout.” I would be interested in knowing of any other novel approaches to meeting the requirement. I also plan to contact Kitchenaid for their input.

What kind of countertop do you have. Many countertop choices have a mitered edge that you should be able to shave down. That might cause issues with stability though, as the countertop still needs to rest on something. I'd suggest talking to the fabricator and asking them if they can think of some other type of support.

Look for a different brand cooktop. Bosch, Miele or Frigidaire. 17 power levels instead of 12 for KA. The installation instructions for a 36" Bosch Benchmark do not require or suggest an opening of any kind at the front. Ventilation space is required at the rear with a rear cutout to the cabinet back if a minimum space isn't designed in. See the installation instructions on page 6.