Anything is possible, though this is outlandish, bordering on the troll-post. All the same, I'll give you my opinion. A dolphin behaves much like a regular PA, though the lower portion will take longer to stretch as it involves more tissue. The real challenge will be stretching the RPA, you will need to stretch that to astounding proportions to be able to achieve what you describe.

I have a dolphin and I'm not picturing this but the initial image I thought didn't sound viable. Then again, I've read your idea several times and still don't get it. You want to do a double lower pa and pull that tissue up through your rpa and place a ring through the holes that are in the lower tissue which you pulled through the top? I am very lost on this one. It's not a dolphin, that's for sure - a dolphin is a design involving a pa and a deep pa connected by a cbb and the idea is that when in use (sexually speaking) the jewelry acts like a dolphin diving in and out of water. I just can't picture what you are talking about.

Dragon, it's not that the tissue is thicker as it's a negligible thickness greater than the glans proper, but it's tougher. I haven't tried a stretch because I don't want to go commissioning a piece with a curvature that won't be so extreme that it causes issues at the cost of having a 1.5" internal tap cbb made at a 6g.