This is an interesting idea, and could have a lot of potential.
I do not mean to discourage your idea or effort, but there are some real concerns for safety depending on the scale of the effort. If you are looking for just your troop and/or oa lodge, where you have some way to verify each member, and are willing to moderate or at least review the content you will probably be fine; however, as soon as you start opening this up to Scouts whom you have not met or do not know well, then all the other problems with these types of systems come into play.
For one, if any members are younger than 13, you may be subject to federal guidelines on COPA
In addition, have you given thought to how you would validate the scouts applying for membership and making sure that no unauthorized persons become members?
The BSA also has some very strict rules regarding communications between adults and scouts. If adults are also members of the site, you would need to think about how the rules could be enforced or accommodated; if not, will Scouts turning 18 be kicked off (or restricted from who they could communicate with)?
Another good start would be to review the BSA guidelines on Social Media
I applaud your initiative. I hope that you can find a good way to bring your ideas to fruition. Either way, you will learn a great lesson about how rules (which often have valid reasons) can infringe on the implementation of a good idea.
While it may not be your intention, I can think of at least 3 or 4 merit badges where an effort like this could probably satisfy many of the requirements.
Best of luck.