hello! my son is 5, a sensory seeker, and in need of routine. He also has meltdowns in stores, takes things literally, and will put things in his mouth. I made him a "calendar"- it is a daily chart, similar to what preschool and kindergarten classrooms have. In the morning, we would put up what we were doing that day; for example- breakfast, school, playtime, lunch, quiet time, playtime, grocery, dinner, clean up, bathtime, bedtime. It was a visual that he had a part in and could see that helped him know ahead of time what to expect and it worked WONDERS. Also, we routinely build obstacle courses in our home. (There are limits of what is and is not okay to climb or jump from.) He uses tents, blankets, trampoline, tunnel, etc. We also got him a weighted blanket for bedtime (he has sleeping issues), and for heavy work (which works WONDERS for him), sometimes we have him put toys in a backpack and wear it around. Also try taking a cup with a straw in it with you places, if he has trouble, have him sip from it.
I do not prevent meltdowns, nor do we stay at home; however, we have learned to see them coming and worked proactively around them. If I know he is reaching his limit, I do hurry to finish but I also distract him with a task. If he is not doing well (the holiday season is always rough) I maintain a routine and not overwhelmed him with a lot of crowded situations and loud noises. Part of it is learning triggers and signs, and part of it is accepting that meltdowns will happen in public (and ignoring the stares....ohhhhh the stares and comments I have gotten).
Good luck and stand your ground!