We're a couple Beth and I still use the hazard lights trick to check the lights while my husband is doing the last bit of hitching. Then finally get him to do brake lights - so don't need the umbrella trick which I must say is brilliant.
Domestics are usual while backing into a site, but imagine this... I'm waiting behind the caravan thinking "Why is he taking so long to put the blinkers on?" Then he calls "Arent you watching?" Me: "Nothings happening" He jumps out to double-check that I'm not blind and the blinkers are really not blinking. Hmmm. So I unplugged it from the back of the tug, blew the dust out of the plug thingy, replugged, marvellous how my eyesight had improved. !!!! Fortunately no witnesses.