Most coventional "over the counter"sissy bars have the brace under the fender .. like the one in these pics.. or this one...
One thing I don't like about this type though .. is that if you use a tire with a little girth to it.. it will want to touch on that bracket as it curls under the fender ..

However .. I rarely.. (and I mean rarely) use any sort of sissybar sticking up .... I usually have the side rails made to fit the application like the Beast .. and this one ..... on this one as well... This one uses ones that slip into a pair of stationairy tubes on the frame...

As Street has said .. they both work just fine.. Just a little more clearance with the separate supports..

Build it the way you want it ..... then learn how to ride it like you own it..
www.lowridersbysummers.com