Easily removable from the 40 man:
Fernando Abad
Matt Harvey
Thomas Eshelman
Zack Burdi
Conner Greene
Eric Hanhold
Travis Lakins
Konner Wade
Spenser Watkins
Brooks Kriske
Austin Wynns
Nick Ciuffo
Pedro Severino (non-tender candidate)
Kelvin Gutierrez
Richie Martin
Pat Valaika
Thats 15-16 depending on Severino. Throw in a couple waiver claims and its easy to get to 40 even adding the prospects they want.
This probably deserves it's own thread (40-man roster decisions), so it's easier for you guys to do it ...
...but I'm not sure how I feel about using the umpire to stop the pitches. I mean, it would create some 40-man space but eventually the umps would probably start getting annoyed, at least until they call Adley up. Probably not that much different than when Severino was back there.