That affects a lot of people with oversized support materials.
She could mount two dowels sticking out of a wall, then binder clip her sketches together and hang them. She could try a lateral file cabinet and make a lift out basket to make it easy to get to the bottom sketches. If she doesn't mind rolling them, she can make an upright stand from mailing tubes, carpet rolls, etc. 'found things.' She might also try one of those large under-the-bed plastic storage boxes. If she likes old fashioned oddities, she could suspend a large flat shelf from ropes on pulleys in the ceiling. Lower the shelf, find the sketch, then crank it back up out of the way. I say old fashioned because many a women did this with their quilting frames. Model train enthusiasts have done this also. Good luck to her!
Elena