You shouldn't go over 1/3 adjunts and never buy your oats or rye from a food store! These grains are not pre-glutenized and you will end up with a stuck mash. Which is to say a large semi-solid wad of grain that you will have to scrap out of the tun & put on the compost pile.
If you decide to go ahead, cook all of the adjunts until they glutenize. Plan on about an 1 1/2 to 2 hours before starting the mash.
Plan on reading up on using decoctions to unstick mashes. Also, the use of rice hulls to improve sparging.
There are good reasons we buy grains and malts from the pros. They've done all of the hard work to make the grains usable.
Been there, tried that, mulched it!
