I'm planning a home funeral/burial for my spouse.
I'd like some opinions on the best way to preserve the body for 3 days
until buried in a homemade pine box.

I'm thinking that rather than lay her out on the dining table for the
wake, I'd just go ahead and clean her up and put her in the box as
soon as she dies. Immediately, I'd go to the grocery store and get
some packets of dry ice and put under her in the box. I don't really
have any idea how many and how long it lasts.

The idea would be to keep the body at about 50 degrees but above
freezing. I just want the flesh to keep nicely for 3 days then dust
to dust, you know.

Any suggestions?