Quick question about door mirrors

[Toolbox]

Thats what I can't get my head round, wouldn't be able to use the one already fitted without not being able to use the heated rear window, only other way would be to use a timer to run the h/mirrors.

Your thoughts??

Just had a look at the wiring diagram http://bebrs.pie-dabas.net/Webs/Terrano/R20/el.pdf page 107

It shows a timer unit; perhaps one could be acquired from a breaker and wired up separately.