I don't think recon camping will be as much of an issue since it no longer has the beacon and open weapons allow other classes to do the same but better (support = heal and infinite ammo, assault can combo shotgun and sniper, engineer will stay back and carry rocket launchers with a sniper).
Since the sweet spot mechanic is already in the game, balancing it has become the issue. Currently, so long as you are 70 meters or more from your target this mechanic will allow a 1 hit KO no matter how fast you shoot (you don't have to wait between shots just aim and shoot which is what allows camping) so by linking the sweet pot mechanic to hold breath i hope it will balance it out (will need polishing)
A sniper ADS will only cause regular dmg, if he wants sweet spot to activate then he must retain focus (hold breath). This focus can be broken when the player moves or takes dmg. In order for player to gain focus while holding his breath he must remain still for a brief moment and must do so after every shot. this could make the difference between camping and strategic positioning as snipers will be open to being countered, Yes sniper can still shoot with out sweet spot but this choice is what essentially changes their aproach depending on the situation. At least compared to what we have now, it could be an improvement. (Would like to see how other snipers work around this feature)
Ps. If your worry is getting sweet spot shot at close combat, that would be difficult to pull as gaining focus leaves snipers wide open (more likely to get killed, can't hold their breath forever, within throwables distance) its not perfect but I think it would be a good starting point to work from.