Hiya,
Sorry im no expert but as far as I understand it to get paid for any job as a pilot you need a CPL and as such to hold a valid CPL you also need to have a current class 1 medical. Please correct me if im wrong as im just starting out planning my path to becoming an FI and am currently planning hour building in the US for the P1 hours required before starting a CPL then onto FI.
Best regards
Keith