We have the same bed arrangement. It's a difficult bed to make up in the conventional manner. Thinking outside the box is useful here. The original bedspread helps keep everything in place during the night with its wrap-around ends. She pulls up the sheets/covers while still in bed, then gets out and pulls things tighter and orderly. Just takes a minute or two.
The width of the queen bed leaves more space on the sides than we ever use. We came close to buying a full mattress as you suggested this year, but got a screamin' good deal on a Sleep Number queen mattress with radius corners at the foot side. Perfect fit on the standard platform (are you sure it's not 60"?) and wonderful comfort, can select our own firmness level.
But if you don't need the queen bed width, why not put a full mattress on there. That's where we were headed. We considered a twin bed conversion but don't like sleeping alone.
Doug and Cheryl
2012 FC RB, Michelin 16, ProPride 1400
2016 Ram 1500 Laramie Crew Cab 4X4 Ecodiesel 3.92 axles
The Truth is More Important Than the Facts