Good data on your Mg use -- I'm always interested in hearing what approaches others use.
Depending on how
far apart your Mg and other meds need to
be, can you take
meds 3x a day instead of 2x a day, so that you can spread out the Mg intake a bit more? -- such as 1/2 the Mg at 10pm, thyroid meds at 6am, then other half of Mg at 2pm -- or some other configuration that suits? Just a thought.
A good pharmacist might have some ideas, or a naturopath, or your doc.