Steric inhibition of resonance vs. hydrogen bonding
I think the main effect in play here is straight electron withdrawing potential of the oxygens. In my opinion this is a classical BSc question that tries to avoid the grey zones of pka eye balling. 

I would invite you to review the concept of steric inhibition of resonance since I'm not entirely sure I understand your argument there. 

Here's a good starting point if you do not have a text book covering the subject 
https://www.quora.com/What-is-steric-inhibition-of-resonance