Here's one method of many others to install your hinges ... this is the one I like.
Make sure all slots can take the hinges (no surprises when epoxying the hinges). When the slots are entirely cut through, close them by glueing a little piece of balsa to the back.
Put every hinge in a clothes peg and turn all the hinges flat (aligned). Get some regular white wood glue and a small firm pig-hair paint-brush. Cover every hinge center (the round part with gaps and pin) with wood glue (cover, not push it in). This will seal the hinge, but does not bond. When dried don't accidentally bend them. Now insert 24 hours epoxy (you need time) into the hinge slots of your rudder, put epoxy to one side of a hinge and insert it in the slot ... next hinge, etc. (One rudder per go, don't make yourself crazy.) With all hinges inserted in one rudder, wipe of excessive epoxy with paper towel and first check the hinges are aligned by holding a ruler or straight stick to the hinge ends that stick out. Remove the last epoxy with white-spirit and Q-tips. Do the other rudders.
Put your model tail up / wings nose down, insert epoxy into the slots and push in the rudders+hinges. (Now you understand why you need to align the hinges beforehand.) Wipe of excessive epoxy and clean with white-spirit and Q-tips. Maybe put strips of thick/firm paper inbetween to leave a little gap between rudder and wing/tail plane.
Here comes the trick ... when all epoxy has hardened, you carefully twist the rudders and the wood glue breaks from the hinges. Pick away the dry bits of wood glue while twisting and your hinges are free and clean!