I have a mod that is similar to salvage but works the way you would like;
It's controlled entirely through events-- you would say, for example,
onPlayerTouch -> SetPlayerBrickPickup 8x8 1
and then they can place one 8x8. It doesn't change the brick loadout but it does restrict their building options.
Additionally, an admin can /clearBP to get rid of all bricks placed in this manner, for fast resetting.
I'm not really interested in adding some of the polish features you'd like for this mod, though, like the waiting queue and updating the player's brick loadout, but the mod I have now should allow for all the functionality you need, and I can add some events if you need anything more (e.g. an event to do the /clearBP so an admin doesn't have to be there and you can just have it trigger when someone wins).