Wow. That’s a big one.
I don’t actually have a direct answer, but some thoughts:
Our resurrected bodies will be true bodies and fully working (ie no illness); HOWEVER that Resurrection has not yet happened, so those in heaven are pure souls. The fullness of the Beatific Vision will not occur until the Final Judgement (Summa, supplement, question 92 ff). Since heaven and hell are separated, “seeing” into hell would be an intellectual vision, not a bodily function of the eyes–in other words, seeing hell from heaven would not be like looking through some window in the floor. Instead, it would be purely a vision of the intellect.
Heaven is pure happiness. I cannot understand how seeing the eternal suffering of others would be a happy event. Unless, one adds the element that in heaven the saints understand Divine Justice (in a way that we on earth can only begin to imagine) and so they would see hell in the context of Divine Justice and understand that suffering within that context.
Even in heaven, the saints are still learning, and will continue to do so until the Final Judgement. So, at the present time, some saints understand more than others. Perhaps those who are ready (such as Our Blessed Mother) are able to see into hell because they possess the requisite understanding of Divine Justice to be capable of seeing that suffering while not partaking of the suffering (similar to the pain we feel when we see a human body badly mangled and it causes us pain even though we’re only looking at a TV news image).
So maybe that’s part of the answer. Maybe those who are ready can see hell, or even see into it. ??? I’m certainly not saying I know the answer, I’m just offering some thoughts.