Being over 30 with a decade's lifting experience should make you more in tune with your body. It should also make you more aware of your rate of perceived exertion (RPE).
Just like salvaging your joints, the aim should be to have muscles work just as hard as they do with your max triple, without the same load. That comes from simply manipulating how you perform your reps.
The Weights Should Win
Taking a page out of Charles Poliquin's book and applying tempos and pauses will make you forever change your perspective on what weight training should be. However, thanks to plenty of training propaganda, we have this mentality that we should be "winning the war" we wage against the weights; that our time in the gym should be a conquest where we "showed those weights who's boss."
I get it, but in truth, for a proper training effect – strength gains and body comp changes – the weights should "win," not you. Yep, I said it. The weights should safely and effectively break our muscles down. And as long as our egos are okay with that, it'll result in a feeling of true accomplishment and you'll have the physical results to show for it.
Here's what I'm talking about:
My true max triple at the time was around 440 pounds, but I made a lighter weight feel heavy. Doing this and "breaking the muscles down" is not only safer and smarter training, it's also a good way to keep your mind in it 100 percent for the duration of the workout.
This can be applied to virtually any exercise, but especially the big compound movements that you could potentially load to oblivion. It's going to be a huge vehicle for training as you age. Instead of looking at your true PR, re-imagine your PR's by seeing how much you can lift using a 4-second negative and full pause at the bottom.