normal fluorescent bulbs are about 10watts per foot of tube length. Most strip lights use a magnetic ballast, so if the ballast is an 18 watter, the bulb can't run more than 18 watts. If you hooked up a 35foot long tube, it'd still only run at 18 watts.
Electronic ballasts are better, but expensive. Some of them have load sensors, and can read the bulb they're hooked up to, and power it appropriately. With electronic ballasts, you can also OverDrive a normal bulb, tripling its output, but shortening it's lifespan proportionately.
I agree get a power compact light, either by retro fitting, or buying a fixture. www.hellolights.com
sells kits and full hoods too.