If you were the one doing the driving I could see it possibly happening- but in terms of her borrowing your trailer I would just find a way to say no.
The risks are too high- even if she drives perfectly (which no one ever does) you stand to take a financial hit if she ever gets into an accident caused by someone else. That's your vehicle/trailer damaged, your insurance rates which will go up for years until they clear your record.
If she does want to borrow the trailer make sure you are either driving with her reimbursing you for time/gas/expenses- or that your insurance is ok with you "renting" her the trailer.
Does the trailer have locks? The one woman who managed a barn kept people from "borrowing" her trailer by just keeping it locked. No one could get in it- so they couldn't use it.