Pathfinder 1E Reach vs. Large opponents

[Starfox]

Could a medium- sized character with a reach weapon (say a human with a longspear) who is fighting a Large opponent (say an ogre) and standing adjacent to the ogre attack the "rear squares" of the ogre. Those sqares are at the proper range (2 squares). If this is legitimate, would the front of the ogre provide cover to the ogre's "back sqares"?

 

[GMMichael]

1st answer: no.

2nd answer: sure! But you'd be better off treating the back squares as having full cover, so a little more than the standard +4 AC should apply.

 

[delericho]

Huh. That does seem to be a hole in the rules.

I would say "no", but I don't have anything to back that with.