Kevin:
I has been said to me, that no timber should go through the sip to the interior frame. As this opens up the sip to possible leakage of water, either liquid or vapor into the wall.

Also that even a through bolt would be bad, as the exterior part will get cold and the interior part may be warmer and where the moisture condenses is in the wall, again causing problems.

It has been suggested to me, that a block can be added inside the sip glued against the exterior sheet to receive the lag bolt from an exterior ledger. This block will not be the full thickness of the sip so there will be no thermal break. And due to the short length of the lag it won't be able to create any condensation and cause a problem.

So, with careful planning and working with your sip provider, you can plan the ledger height on the sip wall and have them provide an internal ledger for it to bolt to. And if necessary this internal ledger can have internal post to hold it up inside the sip. Sips with internal posts and ledgers are not uncommon.

Hope that helps.