If anyone has a picture of a well designed (if there is such a thing) belly pan I'll all eyes. By using a deeper oil pan and having the exhaust collector under that, two problems arise. No room between the pan & exhaust, and so to surround the exhaust plus be wide enough for a 550 bottom end can make for a bloody large containment.
I've seen hundreds, but rarely any with deeper pans, CB400's or 500's would be great. Anyway it's certainly do-able, just another challenge to make something trick.