I don't see it that way .... if there is a valid reason then I will follow it. Modern car engines no longer need running in .... I go easy for first 5000 miles but that is it. Thes new all Aluminium V6 are modified car engines .... so just wonder the logic in running them in. I asked dealer, he advised as part of PDI they run it for an Hr including a full-throttle max revs run. So if that is happening before I get it ... just can't see why my running in would have any impact.
Using it for 22 mph tow sports is hardly stressing it would have thought.
No Engine maker says it is acceptable to Tow during the Break In period(at 22 mph, there is a lot of Hull in the water, so drag is quite High), adding a Skier or Wake Boarder to it does put more load/stress on the engine. It is only 10 hrs, if it costs too much to do that, perhaps you shouldn't be boating. I can't say if Evinrude has restriction on Towing during the first hours.
Many People here have recommended a Break In Period, and some suggestions on How to do it. If the Rings aren't Loaded and Unloaded, they will never wear in and provide the best Seal, but as mentioned earlier in the thread, it is your engine, and you can run it however you want to. I can't speak for Others, but I really don't Care how your treat your Engine, unless in the Future I was looking at buying it.