Well then you don't want to see it as income otherwise you'll be paying tax on it. As I said I would see it as a reimbursable expense but as it has to go on an invoice it would probably be best to set up a new service item called "insurance" give it the No-Tax code and point it to 'other income' line and then when you pay the insurance also with No-Tax pay it out of the 'other income' that way that line item should always come back to zero.
It is OK to keep the 'other income' and 'other expense' separate, just make sure it's not part of normal income when it comes to Tax time