I grow almost all of those species in my bedroom under t5ho on a 4' wire rack like that (I have my pygmies outside). They're doing just fine, but what I might suggest you consider is that although sundew leaves don't grow too tall (except for those capensis guys), the flowers are another matter. As I'm typing the flower stalk on my capensis typical is reaching 14" from the surface of the pot, with 4 more flowers to bloom, so I'd say around 15-15.5"? I used to have my dews on a shorter shelf and I'd just cut the stalks, but I find I really enjoy watching the flowers bloom. And soon I'll have seeds to give away!
I see you've already said you don't have enough room for a 4' wide shelf (yet I'm sure ^^) but if you can get some height, you should be able to enjoy some purdy flowers. Plus t5 lights with reflectors get hot, so the distance will keep your plants from frying.
edit: I got myself a fancy retrofit kit for a 4 bulb t5ho with what I'd read to be very popular reflectors. Turns out, they work a little too well. My plants were frying under 4 bulbs, with temps rising about 12 degrees F above ambient temperature. After I shut off 2 of the bulbs and added a fan, my plants seemed a lot happier. BTW 3 sides of my rack are lined with mylar. This was only my experience and I'm no expert, just reporting on what I've seen. I hope this helps!