my friend once facetiously commented about how we should melt some lead and fill my bike's frame with it, thereby rendering it more stable in a stiff wind. (i'm 130 pounds and easily buffetted around)

now i see in various topics mention of heavier handgrips, and footpegs being a way to combat vibration.

are there other places to choose weightier accessories that i should know of?

Wind that makes you unstable is not vibration. There is really no way to add enough weight to change that. Now then pegs and grips that reduce vibration is vibration from the engine not wind. Yes small bikes to get affected by the wind more than heavy bikes. That you will just have to live with. You could add lots of accessories but you wouldn't add enough weight to be much help in wind.

i have to agree that adding  weight to the bike isn't going to make it much more stable in the wind, depends on how 'buffeted' you are being and are prepared to put up with.
i once rode a z200 in a gale for 180 miles, not a good idea but still didn't lose her.

i can just about touch the floor on my savage and manage to keep her upright, i know that being able to put your feet flat on the floor helps your stability -  but to be honest haven't rode in her in serious wind either - probably go right over if i did.

also i would have though that adding weight to the frame would seriously infringe on her handling and make her heavier for you to handle, manoveure when stopped etc.

i suffered from vibration to the point that my hands went numb on long journeys and changing the grips to rubber ones helped, but vibration on a big single is something that you live with!

as they say 'my vibrator has 2 wheels!'