OK. Thanks. So just to recap.
1. I have shot metered manual, with an MX, since the mid-eighties.
2. Intentionally crippling the MX by pulling the batteries out is artificial and for me, anyway, doesn't really work.
3. I have an unmetered SL. Shooting with it does work.
4. I'm not in the market for more cameras.
5. My question has been, can the MX lenses be mounted on the SL.
6. There seems to be no really good solution.
7. The one possible way without losing focusing range nor changing the effective focal lengths, and that is with a modified one-stop losing teleconverter at the back and a one-stop (presumably) losing wide-angle front-end, is not good optically nor recommended.
8. I guess I'll just need to explore the limits of 55mm:1.8 for when I want to shoot unmetered. And save up for more good M42 lenses, perhaps.
Thanks, guys.