A walk-through transom would be great, but don't think it'd work on our boat.
I've seen Parkers that have it but seem very narrow, designed for fish more than a person walking in.
We dive single steel tanks, full foot long fins. As far as thermal protection we range from lycra - shorts these days, to 3mil with a hood-vest around December - January.
The boat came with a Christmas ladder that can be used without removing the fins, but I always find them to be too vertical for my taste, plus our long fins are akward on them. Great when everything is ok but we didn't think we could bring each other up in case something went wrong.
Here in Pompano Beach unless we go out for blue waters, the response time when calling the Coast Guard is couple of minutes. Off our Panama City Beach dive sites response could be 20-30 minutes. That was the thought behind the wide ladder with handles and a friendlier slope that lets you time a wave to push you up each rung.
For the line on the side, we are implementing that right away,
@Johnoly comment reminded us using that line on the side when we anchored. We made a point of keeping it just short of the prop, in case we forget to bring it back. There was no reason to stop that practice we don't carry cameras and keep the gear on but why not have the line out. If is needed is there with minimal effort.