I wouldn't say this is overkill and setting up the like-for-like redirects from both domains is the ideal approach. Your approach makes the most sense for maintaining rank and as much authority as possible.
That being said I have never had to migrate two domains to one brand new domain. We have handle straight one to one domain migrations with decent success, although we did see a slight dip initially. Please let the community know how the migration goes and any lessons you learn along the way.
Good luck!
