super weird hand
You say SB is a decent reg? His play seems terrible. Leading out as the only one who drew 2 and then even 3betting without a pat hand is ridic.
I think preflop is fine, given you have a gutter and therefore less outs this might be one of the few 1 card draws that i wouldnt cap myself.
After the first draw we probably can't fold anywhere with the pot being this big from preflop.
After the second draw tho when we make no.5 and SB leads after drawing I'm definetly raising. SB already did some weird play on the flop where he 3bets when still drawing, he might still be drawing and even vs his pat range we should be well ahead (unless his 3bet OTF means that he always has a wheel draw like 7532, then we might be behind of his pat range). And we should always be ahead of BTN if he decides not to put in the last bet on the flop.
As played i would value raise river for the same reasoning.

1. BN raises, SB raises, I call 54322, BN raises, call, call.
2. SB draws 2, BB draw 1 (I get J5432), BN draws 1. SB bets, I call, BN raises, SB raises, call, call.
3. SB draw 1, BB draw 1 (I get 85432), BN pats. SB leads, I call, BN raises, SB calls (he is all in), I call.
4. SB pats, BB pats (85432), BN pats. BB checks, BN bets, BB calls.

• 1. I would 4b to charge the btn , who has the weakest range. And its not uncommon for the sb to 3b a 2 card draw.
• 1. call
• 1. You should raise and cap if possible, Btn most likely holding is a weak 8, Some bad players sometimes have a 7. But this is to stronge a hand, to not cap vs such a passive/weak play from the btn. And sb looks like he just wants to get all in.
• 1. lead out and call vs a potential raise.