If the belly cover on your Ameri-Camp is like Forest River trailers use, it's probably a black corrugated plastic material that's held in place with numerous screws.
How heavy is the new electric sofa? If it's heavier than the original, are you sure your slideout can handle it?
2011 Rockwood Signature Ultra Lite 8293SS, 12K Equal-i-zer
2016 Ford F-250 XLT SuperCrew, 6.2L, 4x4, 6'9" bed, 3.73
2010 Rockwood Roo 23SS (2012 - 2014)
2009 Ford F-150 XLT SuperCrew, 5.4L, 4x4, 5'6" bed (2012 - 2016)