Installing the PS and ATF coolers in front of the radiator will not materially impact its cooling performance. You want them installed in tis fashion as installing them behind the radiator will force all the hot air from the radiator over the other two coolers.
I have installed both the factory PS and ATF cooler installs on my '07 even with the little air redirector thingie. Not a big deal to do any of it. With aftermarket coolers you will probably have to do a little installation engineering but again that shouldn't be a show stopper either.
M