I have a GLA 91-b, which has the same dimensions. A few notes on the arrangement. First off I agree with the previous poster(s) adding some height to the slope will definitely help with creating depth in the arrangement. It will make it seem much larger than it is if you do. When building the slope I found it useful to insert toothpicks cross wise and vertically to maintain the the height without sagging.
I have a twin tube T-5 arrangement over my tank and I would suggest looking into an adjustable suspension kit for yours. The substrate is very close to the light and the T-5's are very powerful. Algae issues are pretty likely without moving the light further up. During the emersed growth this is not a problem, but once submersed it may rear its ugly head and quickly.
Personally, I feel that that the tank is underfiltered with a rapids. (In fact I feel the rapids isn't enough for most planted tanks other than true nano's, advertising aside.) Getting sufficient water movement in a tank this long, in my experience, required more filtration than an XP1 could provide, which is in turn far more filtration than a rapids. I will be using an eheim 2026 for mine once the emersed period is finished. Again, this is my opinion and your experience could be far different. A powerhead could alleviate the issue of water movement.
One other thing I have noticed with this tank style, is that evaporative loss is really fast with this tank. I had a custom glass top cut for it to slow the rate, and really think it is helpful with this type of tank. I know not everyone likes the look of it, but if well done it can be nice. Of course I live in a very dry climate and this contributes to the problem but I think it is something worth mentioning.
Anyways, best of luck. It is a really nice tank to work on, easy to maintain and certainly gets more attention than most little tanks.