You know me so well...triathlon is a hobby bro, you sound over-trained :)
Not sure if you're talking to me, but I will address a couple things you have written.
First, this whole idea that you can't PR at 43? You've given up. You've quit. You're only 43 dude. 43, there are still guys finishing first overall at large races at 43. There are dudes winning 140.6s in their early forties. Do you recover slower at 43? Yes. But that's not an excuse. You can still PR. Don't take shortcuts and don't make excuses
I'm 43 too, and I'm faster in some ways then I was when I was in my twenties. Back then I recovered quicker and probably had more explosiveness, but now, after years of dragging my ass up mountains, dealing with General Life bullshit that requires an endurance beyond that possessed by your typical Young Buck, and just surviving, the mental game and just the general stubborn-as-fu#kishness level is there in a way that I never had in my twenties or early thirties.
Second, you listed your T level as a little low. You do know there's a range for such things?
Did you ever get a tested when you were younger? You might be the same, higher, or lower than you were at a yoi ger age. People are different. If you're that concerned about your health, stay away from supplementing it. Down the line it can hurt you.
That and the whole you'd be cheating thing.