You could load that T5HO fixture up with fans and heatsinks to keep temperature under control, but that just adds $$$ to the bill, and you gotta consider whether it's worth it. Because of their efficiency, you could probably get away with having two T5HO bulbs rather than 4--they put out about as much light as two of their T8 brethren (very roughly, a 54W, 4' T5HO bulb puts out about 5,000 lumens while a 32W, 4' T8 bulb puts out around 2,800; the same calculus applies to 2' bulbs as well but I found lumen ratings for 4' bulbs on Google first!). Not to mention the fact that more of the lumens produced by a T5HO bulb are useable due to the nature of the bulb - narrower tube --> smaller light source --> reflectors can more efficiently redirect light towards your plants. Browsing the site that swords posted, I see they sell a two-pack of 2' long, 1xT5HO fixtures for about $48. Not bad. Two T5HOs will probably still run a bit hotter than four T8s, but the difference would be manageable if you ask me. That all assumes you're satisfied with the amount of light you could get with 4x T8 bulbs such that you'd be willing to consider fewer T5HOs to achieve the same light levels.
I sound like I'm evangelizing T5s. Well, I sort of am, but I don't use them and I don't have plans to. T8s suit my needs, but then again, in an un-airconditioned apartment in NYC, temperatures become a REAL concern in July and August, and I need to build my setup around those constraints... meaning that lower-heat light fixtures are an absolute must. But, sure, in an ideal world, we would all be using T5s
With regard to the T8s specifically, I never had great luck looking for 2' long T8 tubes, but
this could be an alternative. It's basically a 4' T8 bulb folded in half. Grab two of these and the appropriate fixture and you'll accomplish what you need. Thing is, I find 4' fixtures much more cost effective for some reason... but you have obvious constraints that put 4' bulbs out of the running.