Editable rests in percussion

I really love being able to edit rests in percussion staves now! Am I correct in thinking that we can only edit the vertical position or delete them? I was hoping I might be able to extend my force duration rests into the kit but it looks to not be possible.

Yes indeed. For the time being at least (it may change in the future), rests that you create with forced duration still go to the actual instrument, rather than to the kit.