tail buffeting and leading edge fillets, strakes

I've recently bought a little rag and tube homebuilt. It's a Stits SA6b
"Flut-R-Bug". It's a tailwheel version and had some cosmetic mods so
that it is a fairly attractive little bird (relative to the butt ugly
original configuration). This is a midwing, strut braced design.

There is some buffeting on the horizontal tail when the plane is banked
30 degrees or more. I've been told that it is turbulence from the
wing/fuselage junction. The published fix is to make leading edge
fillets (strakes). I've seen similar tail buffeting in other similar
size and configuration airplanes. In the Schweizer 1-26 glider for
instance, this buffeting is greatly reduced by sealing the gap between
horizontal and elevator.

I will be sealing the control gaps as a matter of course and will be
(attempting) to make some leading edge fillets. The fillets don't have
to be large. Something like 12 inches long at the root and extending 9
or 10 inches out on the wing. The current plan is to hotwire some foam
forms using airfoil templates and fiberglass them.

I have two questions:

How much of the buffeting is due to the horizontal/elevator gap?

Do the fillets need to match the airfoil or would a generally
streamlined shape do just as well, or is there a third option for
determining how the fillets should be shaped? (simplifies construction
if I can just bend them out of aluminum).

Thanks for the advice,

Wallace
Glasflugel H301 N301BW
Stits SA6b N5423M