coming back to the yard tonight (near A1 blyth services) from the M18
Someone flashes me and points out my back lights are out, Im around 4-5 miles from the yard, and the S/B A1 hard shoulder isnt the best place to stop and investigate the problem. My intial thoughts are that the electrical suzie has come loose from the trailer. So causiously I decide to head for the off ramp at blyth before stopping to check the light fault. It turns out that all the lights on the trailer except the indicators are out, my headlights and indicators, it turns out are working so I decide to stick the hazards on and crawl the last 3/4 mile to the yard to VOR the trailer.
upon investigation the back lights on the tractor are out too, so I check the fuses on the CF and find both 10A`s are blown, luckily for me I carry spares.
In an emergency just to illuminate the rear end you could try putting on the rear fogs.
Carrying spare fuses are better than carrying spare underpants 
same thing happend to me today, no marker lights both sides, brake lights working, i just called the called gargage out.
or you could remove the fog lamp bulb(s)and replace with tail light bulb to get you back.