Is it safe to mix methylated spirits with isopropyl alcohol? I have about 200ml of methylated spirits and 500ml of 100% isopropyl alcohol that I want to mix together in a plastic drink bottle.  I will use it for fuel in an alcohol burning stove while camping.  I can't seem to find any other information about mixing them so...

Is it safe to do so?
Is a clear plastic drink bottle OK to keep them in? (worried about melting the bottle - adverse reaction)
If it is safe to mix them, will I end up with a more flammable mix?

Thanks for any help!
Yes, as far chemical safety is the concern. No dangerous reactions nor dangerous phenomena will occur. The mixture, a solution to be more precise, will retain at least qualitatively the properties of the two components, eg will be a disinfectant, a flammable liquid, a solvent, and so on.
Flammable materials are better stored in separated containers in separated places.
For the case in question, going camping with two small bottles or one double sized bottle in the backpack won't make any real difference.