Hidden rolls initiated by player possible?

Is it possible for a player to use a macro that is ONLY seen by the GM? Example; /em attacks @{target|Name} from a distance with her magical long bow and rolls [[1d20+1+@{Range}]] vs AC @{target|AC}. Damage = [[1d8+1]] In the above example, I don't want the characters to know/see the "targets" AC. Maybe something like: /em attacks @{target|Name} from a distance with her magical long bow and rolls [[1d20+1+@{Range}]] /wh gm vs AC @{target|AC}. Damage = [[1d8+1]] where, wh =whisper hidden (lol) A hidden roll would also be useful for any check that a character makes where the level of success is unknown; perception, stealth, bluff, disable device, etc. As the GM, I would see the results and then narrate that information to the player/party. I like the players initiating as many rolls as possible. Pardon me if there is an easy fix for this. I'm very new to r20. Any non-API suggestions? Thanks

The player would still see the roll as it is a whisper between him and the GM. It would take an API (I know you asked for any non-API suggestions) or have the GM whisper the roll to himself.

Even if you achieve this (such as with an API script), the player could still create another macro to tell them the target's AC.

I'm not really worried about my players trying to "game" the system. I would just like to have the players in control of as many rolls as possible, yet keep the information their characters wouldn't know out of plain site. I love the simplicity of using target in the macros, but I want to keep my "GM-only" information to myself without having to make all the rolls myself. My example in the OP was specific to target|AC, but I think having the ability for a player to initiate a /gmroll could be used for other types of secret/hidden checks as well.