"Worth it" or not is an entirely different conversation that would require a lot more information, so I'm leaving that one alone. As to converting twin beds into a queen my answer is this; everything is "doable" when both time and money are available. A lot of times you'll find a holding tank underneath at last one of those beds, and in the case of my older Southwind, the inverter/charging system is under my rear full. I have tons of people, however, convert those twins in that vintage RV, so yes, it's a simple enough project. Without seeing pics, no way for me to see, but often times it's as simple as pulling up the existing mattresses & plywood, putting a sold sheet of plywood in place, and slapping a mattress in there. I'm sure you case easily modify the existing framework and it shouldn't be too big an issue. Of course, I suppose all this conversation could be for naught if it's found out the center cabinet supports the rear framework of the roof, but that would be a little shocking I'd think.
Post up some pictures and you might get some real, knowledgeable advice as opposed to having to rely on my less-than-educated answer. Good luck!