Even if you change your avatar on Gravatar to include a hat you've got the problem of transferring these onto Answerbank. I did a temporary change to test the system and this went through on AB a few days later- but now, I can't change it back
factor I did have that problem, my poppy one came through about 10 days after I'd changed it (too late in fact) but I changed it back successfully with a 24 hr delay.
Will it go above or below your halo?
I just found a hat picture, copied it on top of my old avatar in Word or a picture manager, took a screen print, then cropped it and put it on Gravatar.
There will be a better way but it does the job for me