They would be longer than the 30 inch tank they are intended for

Back to the positives of Super High Output lights; the cost per output of these lights is a major attribute of the SHO.
This is especially true for planted freshwater aquariums when cost is considered since these lamps do not require expensive ballasts (SHO are self ballasted) and generally cost $30 and up per lamp.
Each time you change the lamp, which should be just as often as any other fluorescent light such as the T5, you get a fresh ballast, so replacement ballasts costs ARE ZERO which in fact DO HAPPEN with T5 and other fluorescents!!

Odyssea T5 Quad Timer 6500K Aquarium Light LED Freshwater Plant 24 30 36 48 72

I am planning on making a Youtube video on what to buy and how to build a DIY T5 aquarium lighting for 24" , 30" ,36" and 48". All you need is your current factory T8 fixture. They are real easy to gut. Once gutted there is really only three wires that need to be installed/capped. Save big money. My Flip video is on it's way so stay tuned.

There's a coralife 30" T5HO light that has 30" bulb

Aquatic Life Light T5 HO 4-Lamp 2-Lunar Aquarium Light, 30-Inch ** Continue to the product at the image link. …2-24W 2 --> 30" 30-1/4" x 9-1/4" x 3" high 124 2-31W 2-31W 2 36" 36-1/4" x 9-1/4" x 3" high 156 2-39W 2-39W 2 48" 48-1/4" x 9-1/4" x 3" high 216 2-54W 2-54W 4 --->Downloadable Coralife Lunar Aqualight HO T5 Aquarium Light Fixture…

30 Inch T5 Fluorescent Light Fixtures - Marine Depot

This AquaticLife T5 HO fixture offers 420/460 nm, 700+ nm and Lunar light in one streamlined unit controlled by a built in digital timer. The AquaticLife 30" T5 HO 4 Lamp Fixture is for reef aquariums.

Coralife 30 Inch 31W 10,000K T5HO Fluorescent Bulb - Marine Depot