Dwarf rhododendron- terrible idea?

[museumum]

Are dwarf rhododendron as bad as full size for invasiveness?
I've a strip of rickety in the shade of a beech hedge that gets only dappled sun. Nothing but weeds(grass) and bluebells grow there.
My heathers grow very well so issuer the soil is relatively acidic.
I'm thinking dwarf rhododendron might help???

If you are going to say no / warn me off - any other suggestions instead?

Rockery not rickety ffs!

Mine aren't, but they could be azaleas! Why not try a couple, you can always control them.

Yes. I think I have to try. The rockery is 2-3m front to back and about 10m wide and it's the strip of about 1m all down the right hand side front to back that's just awful. Cause of the hedge.