Hi Vafann.
I think I know what you mean but we stuck within the restraints of what the program can do.
As you know the

icon and and Manage Attachments is what we're stuck with.
Right now bushes and other tools can be uploaded to,
Forum: Photoshop Brushes
Share & Download Adobe Photoshop Brushes and other drawing & painting tools
Images can be posted at,
Forum: Show-Board
Post your artwork, ask for critique, show off, and help others learn through example.
Now I know what you mean about being organized and easy to find but vBulletin
isn't setup like a search-able database for searching and finding specific images.
It doesn't even do a great job finding specific posts.
The only think I can think of is for you to start a new post in the appropriate section and post your high resolution images in that thread. When you have addition images you can post them in the same thread.
If the jpg's are larger than what's allowed, you can put the image in a Zip or Rar folder, then you would need to provide a thumbnail.
Another option is linking from a photo sharing site that doesn't compress the file.
I'm happy to work with you to figure out a good way to make this work.
Steve