Can a WDL10 daylight switch be used to switch a higher load than the unit is rated for ?

Yes 
Use the day light switch WDL10 to operate a contactor or 600RM

Please note the large LED flood lamps have a very large inrush current and can weld contacts
Schneider electric have some high preformace contactors that switch the load at Zero crossing of the wave form to help with arcing of contacts
 
A9C15030 contactor modular https://www.schneider-electric.com/en/product/A9C15030/ict-plus-20a-1p-uc-230vac/
A9C15031 contactor modular https://www.schneider-electric.com/en/product/A9C15031/ict-plus-hc-20a-1p-uc-230vac/
A9C15032 impulse relay   https://www.schneider-electric.co.in/en/product/A9C15032/impulse-relay-itl%2B---1p%2Bn---1no---16a---coil-230-vac-50hz