kitchen worktop joining (how to tighten bolts)

[tireetim]

Hi, I've just done my first masons mitre joint on a kitchen worktop but now I'm wondering how to tighten the bolts as the worktops are joined above a corner unit below that doesn't have access to get to the bolts ! I considered cutting holes in the top of the units but the position is where two bits of the unit are joined and looks like it will weaken it too much (the top is supporting a carousel thingy). Both worktop lengths are about 3 metres long so I don't think lifting them to join them then lowering them down will be possible without breaking the joint.
Can anyone help please !
Thanks.

 

[Deluks]

Ghost spanner?
Seriously, if can't access it then you can't tighten it, cut the cabinet away and reinforce it afterwards.