greech, its my opinion and understanding of any new hobbyist in the marine section, they will most likely over stock and over feed their tanks and a small tank as this will feel the results sooner then a larger tank, his nitrates will almost sky-rocket right off the bat.
Unlike an experience hobbyist who can do this tank without any filter or skimmer, just using water changes. But for a new person to the hobby, it needs or should be as simple as possible so he/she will become confused or discourage in what their doing.
Like have you known any new comer to the marine section that most of them always had issues on their water conditions. So no, I have to say that I disagree that he should use a simple HOB filter. Im not saying it can not be done, I done it many years ago before there were any skimmers, but I gained myself much hands on experience in the hobby for way back then, we had only two ways to learn what we were doing 50-60 years ago and that was from each other who was trying to manage their tanks and the errors in hands on, back then we learn faster then the young folks of today for if you didn't learn from certain mistakes, you lost many marine live stock and the money we spent back then.
It always amazes me somewhat when looking back to then, the way we had it with no books or Internet for some of the first books I think began coming out at LFS around the time the 70s, it might had been the later 60`s but then again, the books during that time were with little data to help anyone gain much from them. We gained much from hands on far more then anything.
Young man, you can do it either way, for i will say this as well, even by having a skimmer in which is far better to have over any HOB filter, you still could have the problems I spoken about, it is the same for others who started a much larger tank and had expensive equipment and they still failed. It like the one who i bought the MR4 skimmer from, he had a 240 gal tank and failed horribly, i asked him if i could see his tank, it was loaded with algae, so much that i couldn't even tell what was in his tank.
The first two main things you need to do is, not have a large bio-load or over feed, the next is you do your weekly water changes with RO water and make larger water changes if you see your nitrates are rising, even twice a week if it needs it. I hope im not discouraging you any, I only want it that your aware of the problems you will face for know this, freshwater fish are more forgiving where as marine fish aren't.
Buddy