To start, one good thing for sure is that you have a Surveyor that has full framing around all the openings such as slide outs, windows, doors and compartments. This creates more of a backer to secure things to than most trailers.
On the slide out itself, there should be aluminum framing in the upper corners above the large dinette window.
On the side of the coach above the slide out opening, there should also be aluminum framing.
This is where you would want to sink the hardware so that it has something to grab. If you were to miss the aluminum framing, the hardware would penetrate the skin of the coach; however, it wouldn't be grabbing onto anything of substantial support.
As a DYI'er that can't stand paying for installation, this is something I would highly consider/recommend letting the pros do. If the penetrations cause leaks or if the miss the backing, it's on them.
2017 Forest River Surveyor 247BHDS...
...Tugged by a 2016 F250 XLT FX4 SuperCrew, Shortbed 6.2L, 4wd, 3.73...
...Joined with a Husky Centerline TS 800-1200lbs WDH