Pre- & Post- Ride Stretching

I've never been that flexible. When I was a youth I was quite athletic and competed in several sports but even though I followed various pre/post stretching routines I could never do was most folks could do. For example, I've never been able to touch my toes without bending my knees, never. Fast forward many years. Now I'm a much older guy who's lost a lot of ground and is trying to catch back up. I've got the Peloton bike. And I've ridden it every day since I got it (almost two weeks now). And I've been trying to add in the stretching routines. And here comes the question. I need help with doing some of the stretches. I can't do several of them. For example, the one where you grab your ankle with your leg behind your back. Can't do it. After repeated attempts, I was able to get one leg using the opposite arm, but my form was way off and I don't think I was getting the benefit. Are there some hacks I can use to make the exercise work until I become more limber? Perhaps a rope or a piece of cloth around the ankle that I can use to pull up the leg. Thoughts? Ideas of places to go for other exercises to use until I can loosen up enough to do the ones they have?