yes you can do it with single tank. I´ve got a REC wing with a steel backplate that I can mount on my doubles or use it for singles. Here´s my trick, it´s good for me and it could be good for you too. I copied from a friend of mine, that´s been a cave diver for some few years. Take 2 tank straps maybe from 2 old jacket style bcd. Obviously there exist for sure the single tank adaptor out there. But this is how you do it meantime you get that. So , next dismount the plastic plate of the rear of the jacket style BCD, This is what is going to hold the single tank with the harness and the wing. Exactly the way it does it in the jacket style. Next you need to join the bolts from the steel or aluminum backplate to this plastic plate on the back of the wing. Notice that on the middle of all this, goes your wing. Probably depending of the type of backplate you have and the wing style, the holes wont coincide with those of the plastic plate. But generally you have 2 sets of three holes on the wing. Play with with the configuration until you find the heigh you like. Then to hold the upper part of the plastic plate if doesnt coincide with a bolt in the backplate. Place a cabletie, to fix the plastic plate to the hole in the wing.
At the end the configuration gets pretty tight and handy to go for single tank diving. After a couple of times, it takes you less than 10 min, to mount or dismount from singles to doubles with the same wing and harness. Try it =)