So you think the body gets plenty of humidity even if positioned at the headstock?
I'm an anxious one... and MN is crazy dry mid sub-0 temps.
No. I used an Inkbird hygrometer to measure the RH in the body of an tenor ukulele in two different hard cases. I placed a new 49% Boveda Pack in the headstock area of the case, then a pack in the heel area, and then hanging inside the ukulele body from a string. (I used a Velcro-type cord tie to hold it in place.)
This was not a scientific, carefully-controlled experiment. I used an Inkbird hygrometer/thermometer that was +/- 1% of two larger hygrometers when measuring room RH. I also placed the packs inside a Boveda pouch. I left the case open for a day in order for the case to air out between measurements. Note, the lining materials in hardcases, and the wood in the construction of the Oahu I used for this can absorb moisture over a period of time. This experiment was probably too short for this to be an issue.
The RH inside the uke body read 22-25% with just a pack in the headstock location. (I had read a comment in an article that the storage compartment in most hard cases blocks the air in the head area from flowing to the body area. It seems to be true.
The RH inside the uke body read 43-47% with a pack placed in the case by the heel of the uke. I kind of cram it into the space.
The RH inside the uke body read 52-55% with a single pack hanging from the strings into the body of the tenor.
If you are worried about the pack providing enough humidity, I encourage you to get an hygrometer as well. The Inkbird remembers the highest and lowest readings as well as the current one.
The Boveda and the D'Addario pouches have a permeable coating inside the pouch that is supposed to prevent a leaking pack from damaging the instrument. I use it because I think the cloth is better touching the finish of the uke than the paper of the pack. (No proof one way or the other.)