In your scenario, who is the DH/1B when Vaughn or Eloy take a day off, or Eloy is in the OF? Particularly against RHP?
I like Sheets on the bench for that role, and for late-game pinch hitting opportunities. So my bench to start the season would be Sheets, Leury, Romy, and Zavala. I don't think it's necessary/worth giving a roster spot to Marisnick/Hamilton/Reyes. I'm fine with Leury in CF once every week or so (Leury is a better CF than RF), and Leury/Romy in RF.
Give Romy a shot to prove all the offseason work we've been hearing about translates to success. If he isn't cutting it over the first month of the season he can be sent down and one of the minor league OFs can be brought up. But if Hamilton or Marisnick are given a roster spot out of Spring Training, even if they're struggling offensively (which is likely) they'll be given a long leash because getting rid of them means they need to be DFA'ed. Romy's spot can be temporary. Leury is going to get a few months on the roster regardless, and I'm pretty confident he can have a bounce-back to being a useful back-up after an injury-plagued season, if he's used sparingly. If not, and other players are showing they're more deserving, he could get cut in July.
Injuries can throw everything into a blender, so it doesn't make any sense to be cutting players now that might be needed later on.