I bet you could get in on a Planet Fitness day pass. They are a no-frills gym over here and they will email you a one-day trial pass for free (at least they did pre-Covid). There's one not far from the airport and a couple others in town. I'd recommend checking out their website.

The lockers run small so you may have to get creative on keeping tabs on your luggage. You'll also need your own soap, shampoo and towels there.

Safe travels and enjoy.