Using maida + bread flour to create AP flour substitute
Yes you can. 

Truth of the matter is... If you work in a pastry shop (which I did for a number of years), you use hard flour (high protein) for bread. You use cake or pastry flour for, you guessed it, cakes and pastries. If you really need an AP flour, it's fine to blend.

However, I was taught, and still to this day believe, that AP flour was created for home use only, back when people weren't super-sophisticated and didn't know (or want to know) the differences in flours. That was for a baker, who was supposed to have a real deep understanding.

I only have hard flour and Swans-Down Pastry Flour, and I use one of those for whatever I make. I would personally use the bread flour for my banana bread, and I would make it 'just mixed'. I am then not developing gluten from the protein. Also, protein is not gluten. Gluten is created by the mechanical mixing of the proteins.

Long story short, blending the two is fine. That's what AP flour is - a blend.