I think you could do that. We don't have the Scamp
here at home so I cannot double check but we always stashed our sleeping bags and blankets in the 2 underbench compartments (reached by lifting the bottom cushion). And there is also a center space, with a door where other things were stored. It seemed like just open space under there - I don't remember running into anything.
I think it is a great idea for an adaptation. In fact I think I've seen something similar done by someone on the Scamp
Yahoo Group. I know for sure that the bunks have been removed by others. If I can find the pictures I'll post the link....might take a little time to research it. You could also call Scamp
and talk to them about it. But I think it is feasible.