That would be fine.  I will check if forum already has that ability, and post.

Does not seem like this forum has that feature or ability to upload directly a pic for the profile, and like you said you can identify your own picture for your avatar by indicating a web link in your profile.  You do have the ability to upload a picture or multimedia for a post.
What I can do is create a Topic or Category where memebers can post the picture they want to use, and reference the link of the uploaded picture on the post.  

One would simply Right-Mouse Click on the picture after posting it to the topic, and then choosing properties and copying the URL (web link) and indicating that in his/her profile.  I know that is extra work, but for now that is the only work around I got for you, unless I locate that feature and it can be enabled for the forum.

How about the above method for now?