I do have some sympathy because DF groups are typically awful at that fight (outside of JP datacentre, at least) but I don't think altering the iLvl of drops is a good solution. T5 already has the best reward of any fight, which is access to current content.

As people have said, slowly building a linkshell of players who want to progress at your level seems the way to go. Adding a mount or something to the drop table might increase the number of people running it but anyone serious about doing so is likely just to run a farm group with people they know can one-shot it.

I can understand not wanting to leave your FC but building a core of players from your server or even joining/forming a static don't require leaving at all. You'll get there eventually, it just might take some time getting to know folk.

Good luck