Avoiding the bad leg cramps might be as simple as an average speed under 5 m/s, which makes me feel like an utter slug but a slug who must acknowledge that the cycling isn't happening as much as once a week, never mind more than once a week. (Curse you, combination of deadlines and determined work ethic!)
This was not a planned loop; this was a "let's go down to the Martin Goodman and see if I can make it back to the Cherry Beach Chip Truck if I go out Tommy Thompson" sort of thing, and then I went up the Don instead of straight back home because I am very bored of the parts along Queen's Quay where there isn't a bike path or bike lane and one must play "what will we have to dodge today, Brain?" with extra bonus "crush, concuss, or contuse?" rapid prioritization skills testing.
Tommy Thompson Park is an artificial breakwater/harbour extension thing, made out of excavation fill and building wreckage (there are place in the still-being-added parts where you can find yourself riding over ten metres of broken tiles, pounded roughly flat by being run over by a bulldozer; as tyre tests go a fairly convincing one) and it has been, historically, almost completely left to its down devices to turn into whatever sort of urban wilderness it wants.
I remember when this view was a blasted heath of broken bricks and a certain sparse quantity of struggling forb; it doesn't take the prying roots all that long to turn bricks back into mud.
The lighthouse at the tip of the park; if you go and build something 5km out into the lake, it's presumably polite to provide encouragements to the shipping to avoid running into it.