I put our epis, my inhaler, spare mini bottle of saline solution, benadryl spoons for DS in a gallon ziploc and put it in a tray with any other pull items in our carry ons. We usually have a quart bag with some snacks (squeezy sauce, guacamole packs) that need to be pulled. I've had questions about the epi-pens--not problems-- I don't carry a letter and the labels I stick on them from the prescription label sheet sometimes wear off.
I do wipe down our seats and preboard if possible. Kiddo is contact reactive to some things and I'm contact reactive to soy and gluten, among some other things. Our epis stay within reach of me--I sometimes switch them to kiddo's laptop lunch bag, which tends to stay out through the entire flight so that he can snack. We usually pack lunchmeat, cheese, celery, frozen peas, wholly guacamole snack packs, tortilla chips, and whatever greens he feels like eating. I keep a pack of wipes handy, too, usually slotted in a gap under his carseat (he's young, so he rides in an installed carseat on flights).