After realizing that the previous enclosure wasn't going to work, I dug through my scrap wood bin and slapped together a few 2x2s to build a makeshift food holder. I decided to use one of those birdfood suet bricks, which seemed easier to manage.
I also sacrificed one of my sandwich boxes that I take to work to house the Raspberry PI, drilling a small 3/8" hole for the camera. I sandwiched tack between the lunchbox and the PI in a feeble attempt to keep the water out. I used a clamp to attach the box to the birdfood holder.
It's certainly not the most sophisticated design, but should work as a temporary solution. Here's what we have.
You can see the camera poking out from this angle with the new battery and PI inside.
I let it sit out all afternoon and it actually took some bird pictures, albeit upside down. Yet, it's exciting to see this thing actually work!
NOTE: I took the suet container out, just leaving the food brick. I was worried the birds couldn't get to the food. I should've moved that thread rod too!
Also, the battery held up really well. The PI ran all day as there were some night pictures in the folder. Although, I'm not sure exactly how long as I haven't been including the wifi dongle in the box to conserve battery, which messes up the PI's clock.
So, our next goals: Get the pics right side up and see how much longer the battery lasts with higher quality pics and the wifi left running.