My general thoughts on it (no ranges, sorry, just thoughts):
1)BU opening range is affected by SB and BB defends. SB defends ~20% of his range against BU open, so when SB folds, you are playing against a range that was constructed to be good vs average of 2 players, not against you only. That will affect your decision in vacuum situation to play more tight. In reality, when you have exact BU opening%, you dont need to worry about that and you can construct your range according to his % (basically you are exploiting his frequency at this point if he doesnt change his range at all).
2)Against BU 50% range and minraise you can defend pretty wide. Most suited connectors, most K and Q highs, offsuted connectors with high cards. Problem is, there is a postflop left. With wider range, you become more vulnerable on typical broadway-high-card flop since you will not have a pair very often, which requires you to defend Ahigh and sometimes even Khigh and Qhigh with backdoors, which leads to a lot of tough turn situations where opponent can still play pretty straightforward against your range.
It leads to the point where adding more low-equity combos to your range doesnt affect your EV of calling preflop at all.
3)In reality, though most players still play weak on BU vs BB, they will cbet more often then they will check. High-cbetting strategy negates part of equity of your hands (f.e. K4o has decent equity against BU open, but most of it is Showdown-equity and not Pair-equity, and you will not simply see showdown with your Khigh ever). To take advantage of that strategy, your strategy must implement some loose x/raises with unbalanced frequency towards bluffs. Playing this strategy is dangerous, since you might make some big mistakes chosing wrong flops and turns to bluff.

Yeah i'm a little bit aware of how difficult it is play a very wide range oop since have played a decent bit of HU vs 100% button players who CB a ton, what i was really trying to do was use math to come up with some default ranges vs different percentages. Thanks for the input though definitely tough problem thats hurting my brain today :p

What I would do to try and solve this problem (if I have resources):
1) look at winning players at database and see ev of defending borderline hands at large sample
2) use equity distribution software to see most important type of flops for you hand, then use gto solving software for each of those flops to see ev of your hand for those flops. Then apply simple math to calculate ev of preflop call.