Looking for a side mounted tool box

Having a shorter bed to begin with, I don't want to sacrifice more bed space with a normal tool box. I can't get the wheel well ones either as I have a bed extender.

I have been thinking about the better built side mounted tool box..

Not sure that will work with the bed extender though either as its 4 feet long....

hmmm...

Anybody know of a similar type thing for the tacoma but maybe 2 feet long? or should I just get a flat backed metal tool box, and bolt it to the rail from the inside...

thoughts??

I don't think I can bring myself to pay $300 for the Toyota brand one...