fork for bbPress : a classified ads system. Some questions !

Hi guys !
It’s been a while since i’m developping my own classified ads system.
I made a lot of work, until…
I saw that the BEST solution would be -of course!- to tune bbPress and transform it to make a classified ads system.

There is a lot of possibilities, and bbPress is well coded so it’s easy to use action & filter hooks to tune it like I would like :

-changing the post types used, changing the languages, …

I start duplicating bbPress and changing stuff in it.

My question is :

I see how easy it would be to just change some stuff and make a new plugin of it.
But it’s not a good idea : bbPress will continue to evoluate and I will have to hardcode every update in my own plugin.
I think there is enough hooks to build my plugin on the top of it without having to duplicate all the code.

The thing is :
I would need to have TWO bbPress (plugin version) installations.
One for my forums; and one for my ads.

That means two admin menus; hooks activating only when loading the ads and not the forum, …

Do you think this is possible and how ?

Thanks a lot.

http://wordpress.org/extend/plugins/bbpress/