Thinking about getting a suction cup mirror for keeping an eye on stragglers in group.

If you put the slowest paddler in front, no problem. Lead paddler should also have the skills to slow the group so too much space doesn’t occur and then the sweep’s job is to not let anyone fall behind them. If really needed the lead and sweep could also split the group.

What Sass said as far as group management. It is a little fuzzy between the heading and your full post whether you are asking as a group leader or a regular paddler who doesn’t like being run on by motor boats. Or both. If there is a bunch of jack rabbits in a group, they can be their own group.

As to the bike mirror, I liked mine on a bike and never found it too useful in a kayak, But my husband found it very easy to use when paddling. Give it a try and see what your answer is.