I do commute from the south to ABZ so I'm always happy to stick a boat on my insured towhook.
But to answer your question nobody will hire you a tow vehicle as hire companies can't get them insured. SHb will hire you a landie with a tow hook but you have to arrange your own insurance which you can do for a couple of days via special agencies. SHB charge a fairly stiff mileage charge but they are national and will have something in Edinburgh
Compare the Towbar.com