You can, but you really need something to collect the runoff, otherwise you might end up flooding the place while you're not there. If you don't have enough room for gravity-feed runoff, there is another option . . .
This is part of my set-up. If you look closely you can see it's a pot-within-a-pot system, where the green pots (with drainage holes) hold the coco and sit inside the black pots, which collect the runoff and then pipe it outside through a simple garden hose. You can see the individual garden hoses coming off the black pots in this pic (they go into one long drainage hose outside).
Using a similar system - pot-within-a-pot - you can attach a small pond pump to the drainage hose (if you have more than one pot, you can link the drainage hoses together with Y, T and + sections into one runoff hose, like I've done) and hook it to the same timer as the feed pump.
What happens then is the feed pump pumps nutrient into the pots, while the drainage pump pumps the runoff back into a bucket or tote bag, where you can collect it at your leisure and dispose of it.
Am I correct in assuming you don't have enough head height to fit a bucket or tray underneath the pots for gravity drainage? If so, you can place the pots on the ground and the drainage pump should solve your problem, as it acts like a feed pump - just in reverse.
The beauty of the pot-within-pot system is that a small amount of runoff will collect in the bottom of the catchment pots (black pots in this photo) and act as an emergency reservoir if your main res runs out of nutrient. The roots will simply tap down into the catchment pot and live off the runoff until you top up the main res.
Sorry I don't have a better picture on hand, but I'm sure you can see what I mean.