Check your sills! Paint advice

Checked my fabia's sills and there is rust creeping under the paint. I had odd rusty bit that turned out to be stone chip and not deep rust. I discovered thearea just ahead of the rear wheel is susceptible to corrosion.

There is a fibre/plastic - tar manufacturer rust protection under paint. I used sharpened wood chisel to remove. The metal flaked. A hole has appeared. The rust has progressed under the sill rather than from above from wheel arch.

I've previously used etch primer elsewhere, high build, topcoat, clear coat. Not always that durable.

I bought stone guard spray paint to protect against stone chips which is why I was prepping sills.

I've rubbed rust down to bare metal except some rust in pits of metal. I was going to use rust converter but read it is not compatible with primer.

I'm going to use epoxy p40 isopon and some P38 after curing. I'm using epoxy spray primer 2k. I read I can add putty isopon first then the epoxy primer after curing or vice versa, as long as properly cured.

The reason I'm looking at epoxy is that it is fully waterproof and stops rust.

Can I add stone guard over epoxy primer then top coat 1k then 1k or 2k clearcoat?

If not how would you do it?

Is this correct?

Thanks

Front is not too bad, just behind wing - see image.

Both sides of car rear end of sill are affected. The paint there looked fine and no bubbling.

Since photo taken I've rubbed down rust.

Edited 46 minutes ago46 min by bmbmdmb