any red light with a marker/signal circuit (two brightness applications) will work as a brake light and there are many small trim bulbs for tractor trailers for cheap, walmart has some for $3-5 dollars around here.
IMO you could use a clearance/marker as a brake light if you don't have any markers/running lights for night, but the one pictured if I recall is pretty small, and the sloped lens will project light in a narrow path back (since 2/3 of light is going up and down), making it look less bright. The biggest issue with them is the design of the lens, it will not direct or focus light like the rings the inside of the light chris chose. the prism effect makes the bulb "look" bigger and brighter which aids in the day visibility... just my opinion though.
I have 2 oval marker lights as well as a marker/tail/brake light on my buggy, the stop is brighter but two markers are easy to see. the best option would be a marker/brake light as they can be wired into your headlight circuit for getting home at dusk. if you don't care about that, then wire both circuits to the brake switch and it'll be ultra bright.
these are what I'm using for the bottom brake markers, and they are pretty bright, mine are red, though they did not photograph well.
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200331053_200331053 
