My basic rig

[MikesCreation]

My question is this, should I build the frame so the spots for the barrels are big enough for the entire barrel to fit in, so like 2.5ft (like in my draft below). Or should I build it like 1ft 10inches so that the frame rests on the barrel raising it up alittle?

http://www.mikescreation.com/raftdraft2.jpg