An alternative to crimping to a wall wart is using one of these:
http://www.coolerguys.com/840556029977.html
then you could just drill 4 holes for zip ties to secure the power brick onto the lighting cover and if you wanted to make it more resistant to water, just get some big heat shrink tubing and put it over the molex connector. It might even be cheaper since you don't have to buy crimps, but you do need to pay shipping.
http://www.coolerguys.com/840556029977.html
then you could just drill 4 holes for zip ties to secure the power brick onto the lighting cover and if you wanted to make it more resistant to water, just get some big heat shrink tubing and put it over the molex connector. It might even be cheaper since you don't have to buy crimps, but you do need to pay shipping.