Oh yes, definitely. If you're comfortable with it, you can do away with your sump completely and just do a top-of-tank scrubber. In fact, the original design back in the 80s was a dump-style that filled up a container and then dumped it over the screen and into the tank or something like that.
The main advantage to top-of-tank scrubber is that if you have anything that eats pods
(mandarin, scooter blenny) there is no pump for the pods
to pass through. Also, no sump = less hassle and easier setup. Negative is that you have the scrubber in plain view.
For a 55 you would build it so it had 55 square inches, then build the horizontal dimension so that the screen gets 35 GPH
/inch. The problem however with a single-sided screen is that you have to double the screen size so 100 sq in. The other thing to remember is that it's now recommended that you don't put in crosscut in the tube, so with that much water pressure you may get some spray, so you either enclose the screen or build in a spray blocker.
You also run into a space issue on the top of your tank w/respect to where the tank lighting goes. You would only have 6" or so of space in one corner of the tank.
If you have an idea, sketch it up, scan it, and post it and I can take a look at it.