I've got a 2WPG tank (45x37.5x37.5cm, 60l, 15 USG, 2 x 14w T8 Arcadia Luminaire).
I have no trouble growing Glossostigma in it. I started off with about 5 pairs of leaves (the only bits that weren't rotted from the rotten old pot I got from MA Morden - their were gaps of about 5cm between each pair of leaves, and the petioles were 2cm long on what was there, but I got them to give it to me cheap). That was about 6 weeks ago and it's been a great plant- not growing as fast as I expected it to, but I think each pair of original leaves produced a plant. They quickly rotted off, but each one has sent out a line of new leaves, less than a cm apart, and the biggest ones now have 12-15 pairs in their 'line', and 5-6 new 'branch lines' coming off them, each with 1-3 pairs of leaves so far. They haven't covered the area that i want them to yet, but the leaves they've grown since i've had them in the tank are all still looking great, really bright green, and they've stuck strictly to horizontal growth - the stem joining the leaves mostly runs just under the surface of the substrate, but occasionally along the top. If they hit an obstacle (wood, the side of the tank etc.) they just turn and grow along it.
here's a picture from 21 Nov (sorry, terrible mobile phone quality) which shows the growth pattern it's taking under this lighting. That main strip is now about twice as long as in the photo, and the side branches are developing nicely too.
I've always heard that Glossostigma is a monster and will swamp any plant it comes across, but mine is very well behaved - probably because it's not a very brightly lit tank. This is fine by me, as the Cryptocryne parva it's growing in with are some of my favourite plants, and the Glosso would be gone if it decided to throttle/cover them. At the moment it's just happily growing underneath their leaves. I don't know if it will start to grow upwards once it's filled in the space available to it. I haven't had to prune it yet. When I do, I hope I can just cut out excess portions of it, and not have to pull the whole lot up and replant.
So, 2WPG shouldn't be too much of a limiting factor for your choice of plants. Good luck!
Mark