I would like to see integrations added for the mod mentioned in the title.
I confirm it is available for the latest Minecraft version at the time of writing.

About the mod

Link to the mod page (e.g. on CurseForge): Sophisticated Backpacks

Link to mod source/API: The Sophisticated Backpacks github

What should be integrated exactly

There's one interesting thing with backpacks that I feel could be fun to explore: the Tank upgrade! As we know, Vampires can store any excess blood they drain in bottles to keep a reserve. I think it would be fun to allow vampires to also drain into a backpack in their inventory or that they're wearing without needing to use a bottle and a pump upgrade as an intermediate. Additionally, the Auto-feeding upgrade currently stuffs any food obtained down the vampire's throat, which doesn't have any effect since they need to drink blood to survive. I think that an autofeeding upgrade with a blood-filled backpack could instead feed vampires from the tank, like a morbid hydration pack similar to those a hiker would use.

I can help with

I'd be fully willing to test builds, draw placeholder textures where necessary, and test interactions with other mods like AE2 to make sure there aren't any forms of fluid weirdness.