kat, if you can, let them do what they need to with the old packing case that Sparky came in, we KNOW he isnt in there anymore, he has moved on into our hearts, where he is in permanent residence, and the empty case matters not an Iota, make your own memorial for him in Colorado if you wish to, even if its just his name and dates on a pine board, or a framed pic with a black ribbon in the corner to show that it is a "past picture" hanging on a wall, or simply the place in the heart that he lived in anyway.
He lives on, not in a stone with his name on it, nor a Monument in St Pauls, but in how we remember him.

" The moving finger writes and having writ
moves on, and all your piety nor wit
can't call it back to cancel half a line
nor all your tears wash out a word of it