If you add them, and you think it might be putting too much pressure on the tank, you can build a little stand for the HOB and skimmer. I got a HOB refugium (about 20 lbs when full) so I got some 2X4s cut to size, and made a little box stand- I'm not handy at all, but this was REALLY easy.
Just make sure you measure a few times (while they're hanging on the back) so you get the right height. And you don't have to worry about painting as long as you have a background on the tank.
That said, you should be fine without one