How can I treat or replace steel bolts in aluminum nuts to avoid corrosion?
You could try using stainless steel bolts, dip in an anti-seizing compound like "Coppaslip". Under the head use locking washer, a good option is the "Nord-Lock" it is a 2 piece device, 2 washers that have serrated edge on one side and a series of wedges on the opposite side. The serrated edges grip the bolt head and the structure, the wedge faces face each other. They work by tightening the bolt and the wedges lock into each other, to release you first tighten slightly then quickly release. They are reusable and anti vibration, I used these often when I worked in the mines. Try this site for information; http://www.nord-lock.com/nord-lock/wedge-locking/washers/introduction/