I use cage straps on my road bike. But I'm not riding the TdF - I commute on it. And Im old school - I rode cages before anybody heard of performance pedal designs.

Im thinking there's a good reason why MTB'ers have universally embraced the SPD style of clipless pedal. But since you intend to remain a casual rider, I doubt it will make much difference to you. And there is something to wearing your everyday shoes, if you prefer them.

So get some of the Delta Toe Clips and try em. They will attach to almost any platform pedal and are indestructible.
They come complete with straps and hardware and are $10. If you dont like them, you can fall back on plan B.

http://www.deltacycle.com/Toe-Clips