When I built the stand for my mill I was in two minds about fitting a coolant tray... I never did, and the mill's stand is basically just a frame and not closed up at the top, so now it's relatively easy to get at the feed screws and nuts from the bottom for cleaning, oiling and backlash adjustment without lifting the mill or taking it apart.
The only downside is that it'll be difficult for me to fit flood coolant, but then again, I'd rather go for a spray-mist system when I get around to that.
Regards, Arnold