I assume that what you're talking about is a "pod" cockpit as used in the Sea Tiger and (now defunct) Puffin? I agree that it's an interesting concept with real advantages. The downside is figuring out how to size, build, install and support the pod assembly. The easy way out would be just to use a sea sock in a boat without bulkheads. Perhaps there is a solution that's somewhere between a sea sock and a pod?