Yes you can do single sided gearing, but you may be surprised to find that the spread of gears people use on a tandem is much larger than on a single so restricting yourself to 2 chainrings may not be such a good idea as you would miss out on some big grins.
We regularly use the granny ring and wide range cassette on the tandem for steep hills (up to 25% near us), which on a single bike you can soldier up in 39x23 if reasonably fit and strong. Theoretically you can do this on the tandem as well, but it's much more difficult than on a single - I suspect it has something to do with the fact that we have the gears and we are supposed to be out for a fun ride together not to beat other people up a hill.
Then down the hill we get payback for the uphills and increasingly regularly get the 53x11 spinning. Sometimes on the flat with tailwind this happens too
2 nights ago we literally blew past 3 single bikers grinding up a local hill, still riding in the big ring at minimum 20mph faster than they were. Stoker did threaten to kill me afterwards for making her ride harder than intended, but as I said afterwards I never managed to ride up that hill spinning the big ring all the way up and over the top on my own, so it was worth it.
