ItemFrame Comparator Output

So I had an item in my 1.7.10 mod that told the player the current temperature and rainfall levels (as I varied these values over time, creating effective seasons) which then effected crop growth.

One of the things that was requested many many times was a way to read that same data as a redstone signal.

I did this by backporting the ItemFrame Comparator output logic via ASM, giving myself an event hook.  The default logic was to look at the item's rotation, but I was able to also provide a value based on the temp or rainfall if the item in the frame was the thermometer or hydrometer respectively.

As coremodding is so highly frowned upon, I am looking to insert this same sort of logic into the Comparator via Forge Pull Request.  However I see two possible ways of doing this...

Option 1:

Insert an event to EntityItemFrame#getAnalogOutput

Option 2:

Insert methods to the Item called...say...

hasItemFrameOutput(World, BlockPos)

and

getItemFrameOutput(World, BlockPos)

(also ItemStack?) which EntityItemFrame#getAnalogOutput then invokes.

Option 2 makes more sense for my use-case (my item classes would then override the methods and provide logic), but I am unsure which would be better in the general case / Forge's approach to vanilla alterations (are modders going to want to alter the behavior of a vanilla or other mod's item?).