A couple of things, and I am really not going to address your question, because i don't think your question is pertinent to the issue.
First and foremost, move tables. I know the advice is unhelpful for developing your game, but seriously, 4b bluffing at 16NL is just bad.
Secondly, no reg who is 3betting light is ever going to flat a 4b. So having a hand that connects with the flop is somewhat irrelevant. If you really feel the need, Ax is probably your best bet as it holds the best equity against his 5b range. Junk is just as good.
When considering flatting the 3b, consider that most micro regs play either fit/n/fold or spewy in 3b pots. Either way they are predicable. Identify your villain and exploit them postflop either by bluffing lots on the flop or making hands and letting them bet respectively.
Also, your 4b size seems weird. Should be really small in position, because you will either see a shove or fold.