I wouldn't tie her up and groom her or anything tbh. I would just change her rug quickly, put boots on if you want and put her out. Echo the wearing a hat, gloves, good footwear etc. HOWEVER, I too would be wary about just chucking her straight out however mine would be because of any potential infectous diseases Does your yard not have any sort of initial isolation period for new horses?
Perhaps I'm being a bit dramatic but that is how things like strangles gets spread so easily.