I'd say just design it so you can get to things. I don't know about others, but if my skimmer cup is too hard to get to, it's going to stay dirty longer.
Also, if you're going to bury your electric under the tank in the stand--or install a box like I did--try to design that as far away from water as possible. All it takes is a loose hose from a reactor pump, and it's spraying a power bar with salt water. I've got a pump in my fill reservoir (under my tank in the stand) to continuously stir up kalk--well my water level dropped the other day, so the pump was partially submerged, and it ended up spraying around the lid and saturating a power bar. Murphy's law.