a hba1c of 5.3 translates to average blood sugar levels of 5.9, so quite safely away from hypos really.
The target for type 1 is a hba1c of 6.5, individual targets are adjusted if there is some concern over hypo awareness etc.
To get an average of 5.9, in the presence of spikes in the teens, requires there to be hypos, including some very bad ones, to balance it out. There is just no way around that. So very low A1Cs can be quite dangerous. The mean doesn't tell the whole story, one has to look at sugar variance as well. Ergo, the law of small numbers / aka Bernstein to the rescue, plus drugs like GLP-1 can help lower sugar variance drastically too. It cut mine in half, literally overnight.
I've successfully kept my A1C in the low 6s most of my adult life, but only recently decided this wasn't optimal after reading the "Golden Years" study, showing that longest lived type 1 diabetics have an A1C on average of 7.6.
Glucotoxicity isn't the only thing that matters, there is also insulin toxicity. Hypos can cause heart failure, sudden death, car accidents, comas.
The best goal to my mind is keeping A1C reasonable, whilst minimizing insulin TDD as the primary objective.
To do that, the best way is calorie restriction and LCHF, IMO, but also retreating from the obsession that you have to keep sugars in the perfect range via insulin shots, rather than via urination (and ideally diet to avoid spiking sugars in the first place).
So I'd suggest that prioritizing low TDD over extremely low A1C is the smart move, for both short-term safety and longevity's sake. And lowering TDD while maintaining a decent, middling A1C, is typically achieved through diet and exercise (lean muscle requires less insulin since it's more sensitive).