Whilst the quality of the tank and fittings is without doubt excellent, Methanol IS corrosive to Aluminium, especially in higher concentrations. There is a good reason why Drag Cars, Monster Trucks and for that matter even RC Cars use full plastic Fuel Cells and piping.
I'd strongly suggest you consider including a liner (as with fuel cells) to prevent direct contact between the tank and the methanol to increase longevity as well as decrease the risk of spillage in the event of the tank being breached in an accident or alike.
Alternatively, a vacuum moulded ABS tank could easily be templated off the work you have already done, this would not only be cheaper, but safer in the long run. You would still be able to retain the high quality finish, the easily concealed design and the use of an earls sealing cap
And I for one would be first in queue to buy one!
2016 Alfa Romeo Guilia Quadrifoglio - Metallic White