You might find the info in this thread helpful...the thread is one by one of our mods, and an extremely experienced brewer.
https://www.homebrewtalk.com/f12/brew-age-10-years-121878/?highlight=zymurgy
And if you can get a hold of it, in the Dec 07 Zymurgy Charlie Papazian reviewed bottles of homebrew going back to the first AHC competition that he had stored, and none of them went bad, some had not held up but most of them he felt were awesome...We're talking over 20 years worth of beers.
I even think that he put a couple of the original recipes in the article of the ones that helpd up the best, and even improved. If you go the beer route, looking at that article my be helpful, at least in terms of what worked and what didn't work so well.
But yeah you need to consider an extremely high gravity beer....in fact there is a pseudo Utopia clone recipe thread floating around here.
This would be kinda what you are shooting for...
https://www.homebrewtalk.com/f12/way-way-way-over-top-sam-adams-utopia-clone-91463/
One thing you might wanna consider, if you don't have the setup to handle that much grain, you could consider doing a smaller batch...that way you could fit it into your cooler, and brew on your stove top (if you haven't mastered full volume boils yet) I've done some ehigh gravity 2.5 gallon beers, which I've fermented in a 3 gallon better bottle.
And even on the
Basic Brewing⢠: Home Brewing Beer Podcast and DVD - Welcome podcasts, they have done 3/4 of a gallon barleywines in 1 gallon jugs....
You don't need to make a ton of this....you could even do enough to fill 2 or 3 or even one for that matter champaign bottles and stow it away.
hope this helps.