The lowest profile "practical" B+ motor home I found, we bought with E350 chassis is 9'-10" to the tippy-top of the a/c unit. Other models of the same brand built on the E450, sit 3" higher, I think because the chassis sits that much higher.
If wanting to buy older-used to keep your purchase price down, other older small rigs are Carri-Go, Starflyte, and Telstar. All are of the B+ variety, made decently. The Carri-Go is similar to mine but taller because of a taller a/c unit on the roof.
pnichols list is a good list, just adding to it.