If I were looking at a situation such as this I would probably accept what you have for now and then write in three-six months asking for proof that rent has been paid – bank statements showing transactions, rent book etc.
If no rent paid then you would have something more concrete on which to base a decision of non-commerciality/contrivance. Given the circs it sounds as though it would be easier to show contrivance than non-commerciality.
Only problem is that of course you may end up with an OP to recover.
I don’t agree with your colleague that it’s unreasonable to request more info, but I agree it’s hard to know what clt could provide that would satisfy you that the agreement is above board!
