I have attached my
PC reflectors directly to the wood and even though
PC bulbs are not near as hot as
MH they still will warm up the wood on the top of the canopy.
The last canopy I wired up I put some spacers between the reflectors and the wood surface. If you do this so their is an airspace between the two and then put a fan blowing across this space it shoudl help keep everything nice and cool.