Disclaimer: I dont play HU at all, and play lower stakes.

just to kick off the discussion: I do think that it's good candidate to xback (it would be in regular 6m game), you might be folding quite a bit of equity vs x/r range and when called we don't get to barrel too many turns as overal visibility on most turns isn't great. So, keeping the pot small and maybe have some deception with checkback makes it a reasonable play, imo.

i think bet calling it off is the way to go in my opinion.
Sure when he pots you'll run into some sets and nut flushdraws but those are quite rare and even then your equity is OK, but you'll also run into two pairs which you're flipping, and into flushdraw+straight draw type hands which you're dominating.
When he just calls however you're pushing a TON of equity against his range which might include weaker flushdraws and some random pairs with not much else going on.
If Villain just calls i would probably fold if bet into or check back on a 8 7 6 or 3 turn, would probably call/check back on a 9 turn, and would ship the remaining stack vs a bet or pot vs a check on any A 2 T Q K or a turned Heart.
On a 4, 5 or J turn i would consider (player dependent) betting my hand if checked to me and fold if bet into.

Pretty easy check-back.

Is the reason for "it doesnt need protection" that it is behind vs hands that c/c? So against a Jxxx for example