I did today in the drysuit. A lighter undergarment would have been nice, but I did fine. I worked my butt off on the two missing diver drills though. On the first one, I was the snorkeler and on the way out, one of the divers had a mild panic issue and I had to take them in (real not planned). Came out with another diver and then she had gear issues and couldn't dive once we got to the site. Being the snorkeler, I didn't think to put on gear, I just grabbed my mask/fins/snorkel, and went. This was a mistake and cost us our first victim. Eventually, a DM came out to make sure everything was OK and accompanied the other diver as a safety to go find the missing diver. She found our expired diver, brought him up, and started the surface swim back. The other diver got tired so I got to push them while they attended to the victim. Lesson learned - don't assume other divers are capable of making the dive. Put your gear on and be ready to take charge if needed.
For the second missing diver, I grabbed my gear and was appointed diver by the person in charge and off I went right back out on another surface swim. I bet it was close to 200 yards or maybe a little more. Down we went, we recovered our unconscious diver and began to bring him back. The other diver gave breaths and swam and I pushed to get him back to the shore faster.
At the end of that, I'd done 4 long surface swims in the drysuit with a heavy undergarment. I was tired, but I survived and so did victim #2.