the only reason you didn't know about the oil in the Gator is because you had both sides tightened up with jubilee clips.
I think i'm right in saying that virtually every 1100 has a bit of an oil leak down there at some point in their lives - loads of posts about this.
I would just clean up the whole thing and see if this (oil on the tyre) happens again.. as for the oil in the gator - thats easily fixed - or just as easily ignored. the amounts are tiny and from what I've experienced never seem to affect the level in the FD.
mine was ignored by me for over a year... and the oil level never seemed to move.
Yep - I think the clean and monitor thing is the way forward - I went over it with a fine tooth comb and all the advice I've received says that it's highly unlikely to be the output seal - I can't for the life of me find anything else amiss.
By the way, does anyone else cr*p themselves when torquing filler / drain plugs? I've never bothered torquing these before, but as I've got a new calibrated wrench, I've been using it (set to the recommended 23Nm) but they feel bloody horrible as you near the final torque (that nasty plastic, pit of your stomach 'it's about to strip" feeling. Must be the alloy crush washers I guess. I often can't bring myself to go all the way to the set point on the wrench.