If they'll need them for ASW, sending them ahead of time to air ops/patrol areas will solve that problem. ASW helos can also be rotated between LHA/Ds & CV/Ns, even if they r not close together.
An 075 LHD with a top speed of 25 knots will not be able a suitable ASW platform for a CSG because it won't be able to keep up with a CSG whose top speed is 30+ knots.
The top speed of a CSG is not only able providing wind over deck for the aircraft, it's also about giving your task force the speed to maneuver between different areas of operations and theaters.
An 075 LHD simply won't be able to keep up with a CSG moving between different areas of operations, and will not be a normal "part" of the CSG in the traditional sense. At best, they might be a
separate task force by itself, operating in the same area of operations as a CSG but with significantly reduced top speed and therefore reduced flexilibility to move between different theaters.
Just because 075 can carry lots of helicopters doesn't mean it will be able to provide ASW as "part" of a CSG due to limitations in the ship's speed.
Carrying lots of ASW helicopters doesn't mean anything if your ship is unable to keep pace with the rest of the ships in a CSG.