Would this work? Ignore all the shit, it's just the only picture of it I can find right now. It goes lower, it'll splay out near flat in the lowest position.
It's a Sirui and I got it on sale from Camera Land for $125. It'll support quite a bit of weight and it'll go down to 8". In the picture, the legs are still angled. In the lowest position the legs will almost be horizontal. Light, compact, inexpensive, high quality. Sirui is on par with (some say better than) Manfrotto. They have a carbon fiber model for a couple hundred more but this one isn't heavy. I opted for a basic but solid ball head and that was in the price. Can't remember the model number but wanna say 150 or something like that. Just call Camera Land and give 'em your specs and tell 'em your from the 'Hide and they'll take care of you.
I got this one because I wanted one that could be used in the prone or standing. There's a short and long center post; the short one is pictured. Manfrotto makes one that goes even lower but that's because it has a horizontal arm on top of the tripod. It's nifty, but it's not what I was looking for. I wanted a real tripod, just one that goes low.
This was the lowest tripod Camera Land had that was still a solid, full size yet compact and light tripod that would go that low without using a horizontal bar. I can't recall what the weight limit is but it's 22lbs if not more, at least. Wish I could recall the model but if you tell 'em it's a Sirui that goes down to 8" or so without the use of a horizontal bar, they'll figure it out. Then again, that horizontal bar may be just what you're looking for, I don't know. That one was a Manfrotto 225 IIRC.
Good luck, hope this helps some.