Overlap situations are defined on P.35.
Neither of the first 2 bullet-points apply to an element fighting against fortifications (whereas PO are specifically mentioned) so no, I don't think so. There're some additional issues for fights involving fortifications on p.42, but these don't seem to affect baggage camps. The -1 for having an enemy element in contact with a flank edge also doesn't appear to apply in this situation.
To be honest, DBM/M has never handled fighting at the corner of fortifications very well...
Tim Child