Maybe worth a try.
Currently I am using the RRS L-plate for GFX, which sucks big time! I bought dozens of products from Really Right Stuff over the years, but this is the first one where they failed. It has a sliding left side part, which can be slid by loosing a thumpscrew, but it needs quite an effort to do so as it tends to get stuck and then it only allows acces to the cable door. for access to the battery the whole plate has to be removed, but there is only a hex screw to do so and no hex key is included as it is with some modern RRS L-Plates, like the one for the A7r2.
this one is a total fail, an expensive piece of junk.