ok.. this is my first try at luthierism. im making a neck through 7 string bass in my shop class. ive done a lot of research but i cant find much on dual truss rods. my questions so far are as follows: -should dual truss rods be parallel to the center or to the edges of the neck? -is it necessary to have a longer truss rod for a longer scale (35.5") or will a rod for a 34" work? if so would it be ok to have headstock access? i plan on having 29 frets which would kind of limit the option of body access. -my neck is huge - about 2.5" wide at the nut and 4" at the 24th fret (my exact measurements are at school). is there a rule of thumb for how far the truss rods should be from eachother and/or the sides of the neck in proportion to the width of the neck? thats pretty much all ive run into so far but it isnt unlikely i will be returning for more. thank you!