the fuge is just that.. a refuge for marine life to thrive in is a NON preadatory environment.
Size is important if you are expecting to use the deep sand bed method to help convert nitrates. growing macro is a method of exporting waste AS long as you throw it away. its not something you need to keep, so the fuge size isn't as dependant on the macro as it is for the sand bed.
as for lighting a fuge, people light there fuge opposite thier tank to help control the PH swing. having it lit durring the day IMO has been irrelevant. i'd argue that a fuge could USE a little MH lighting.
your macro will certainly grow faster allowing you to export more waste.
Mike roby used to have a 180g. and a 125g fuge. with a fuge that big he ran skimmerless.
I'd keep it on the system as a fuge and not worry about the size. if anything, i'd add more sand and a Lihts of America PC from HD. (cosco has them cheaper btw)