how do you get a roost like that
There's only 2 setups I've ever seen personally, and specifically, built for that! One, is obviously Rivertard. Just insane. The other is our founding father Brad. I've witnessed Rivertard completely clearing bridges, and also have a hi-rez pic somewhere of Brad hitting the bottom of the Parker bridge (Rivertard was in my boat when I took the pic, dont remember which boat it was, I think the Pickle.), and Brad did it with a fat 20' cruiser! I'll dig it up, I know I sent it to Brad also. Makes my lil Moo (1.0) look like a child by comparison, which I was pretty proud of her for tagging the AVI bridge with a mostly stock JE pump, unmodified diverter and somewhere close to 600 HP with a close to 400' long roost.

What it takes? It's more what you can live with. Brad will be the first to tell you his cruiser is squirrely as hell running that way. Mikes prolly is too, but both of them have decades of experience driving these boats and you will note, there's NEVER another boat underway anywhere near them when they do these stunts in the pics. Including Rivertards famous "wheelie" where the boat is seriously, near vertical and you can actually SEE part of the intake on the bottom of the boat.
But if you really wanna challenge these guys on this, first are extensive grinding, droops, wedges (Rooster booster's maybe), and impeller work. Second, to be able to do it properly, a LOT of HP. Brad does his with probably around 400 HP and change. Dunno how that is really possible, save a big heavy boat. Mike? well, that's another animal. Closer to a 1/2 TON of HP, mods on the pump, droop, etc that would even make the pump designers cringe. Loaders go without saying, and I'm not gonna get into inducers as I don't beleive either of these guys are running one.
Cream of the crop.

Ray