Never had ours pop out and always back up with it hooked up. As mentioned, these are excellent WDHs - I love ours and the self-centering action is great. Good choice on a longer TT.
Internet says that your TT is 35' with a 9K lb GVWR and dry tongue weight of 1035 lbs. With higher TW like this, there's a few things I'll mention. There is also some excellent info. on this WDH in a sticky in the towing forum. Depending on what you get for a TV, the receiver could have a max. rating of 1250 lbs.
The actual tongue weight when full loaded will be in the 1100 - 1200 lb range and possibly a bit higher. When the tongue weights get this high, the bolts holding the cam arm brackets onto the A-frame can potentially loosen and there are a few ways to address this. You could try Reese's rivnuts, but if these don't last there's more you can do. (I welded nuts on the inside of the A-frame tubing.) There is also a heavy duty snap-up bracket available that would be a good idea.
The cams will develop a wear pattern specific to each side, esp. with higher TW. Mark the bars with tape to make sure they stay on the same side. With higher TW, you may only get a few seasons out of the cams, depending on your mileage. They can be flipped side to side to get extend their life.
Make sure you get the correct rating of spring bars and do NOT select based on dry weights. Setup and adjustment on these WDHs is very important. Trailer nose needs to be level to slightly nose down when TV & TT are fully loaded for camping. I had to get a ball with a 1" rise to get it to all work right. I tried nose-level for a while but I find it better now that it's slightly nose-down. Getting the bars at the right angle with correct weight transfer to the steer axle is important. Getting the cams to center exactly in the bar "notches" is very important and will be affected by the tension you put on the bars and the weight in the TV & TT. Takes patience to get it all "tuned" up. Took me a full season of playing with adjustments to get it optimized. Also, you may need Reese's shims between the hitch head and shank if there is too much play. Make sure to take the tools needed to adjust the cam arms with you on camping trips so you can adjust the cam arms if needed. Note that depending on where your holding tanks are positioned, towing with a full tank can affect the cams & bar notches and affect towing.
Almost forgot, a few years ago, the cam arm brackets were curved on the bottom. Try and avoid buying a DC package with these one. You want the later ones that are flat. See photo below. If you end up with the curved ones, contact Reese and they should send you a new pair. On a TT with high tongue weight, it's important to have the correct brackets. Also check the curvature where the bracket mates up with the A-frame tubing. I made some shims to make the bracket fit tightly.
