Panel thickness cannot be chosen from room target temperature alone. Outdoor conditions, operating pattern, door use and joint design also affect the cooling load.
Ask each bidder to state panel type, thickness and documented thermal performance together. Compare options designed for the same room conditions, and ask which assumptions support the capacity and energy estimates.
Include the floor, ceiling, door frame and panel-joint details in the scope. Treat bids with different thicknesses or materials as different specifications.