Sorry, rust stinks, MN Salt / Winter is taking over my 1994 Tercel...... so feel your pain
I have the passenger side 2006 Solara Rocker Panel Silver... already removed and in my spare parts. These are plastic. The rust rocker in Canada, could be cut front & back so the area is flat.
I would spary the rusty area with POR15.... this is a rust convertor that holds up well.
NO UV protection with POR15 so good for bottom of car, but needs to be spayed while still wet with a paint with UV block if any area is sun exposed. The bottom of auto is a good place for POR15. WE use it a lot in the classic 4x4 restor work. It is a black finnish.
Then use a body pannel adhesive to attach the 2006 plastic rocker pannel to the cut off , POR15 covered, area and will be a good repair. Rocks and debree get flug at the rocker pannel, chips the paint, and that is where the rust process starts.
My 2006 Plastic Rocker is not perfect, but in decent shape..... I would be happy with 100
Spay all the bottom with POR15, mask off the areas for maint, the rubber boots, etc
I have used HF Paint sprayer with can on top, used brass fittings so can tilt can so can spray upwards...
This worked well
Also from my research before you get rusty.... Thin Flim or similar product, there are 3 major ones, can be sprayed on bottom of car, the holes, the frames, and will keep the auto from rusting out. I purchased a FL Solara that is rust free..... will be using the Thin Film Spray oil coating on my ride. Needs to be done yearly or everyother year. The grandma car had been curb run over on passenger side.... had car avail that had decent plastic rocker replacement. I had not seen the car in person, so purchased the passenger rocker, passenger door, passenger fender, just because it may be needed and had access to a very nice solara that was rust free to pull these parts.
The rocker is long, but should be less likely to damage in ship vs a metal rocker would. This pannel was put in with plastic clips, the body pannel adhesive would be a great way to attach. Just will need few small jacks or similar. Could also pop rivet, screw. Could also have a body shop do it for your.
I think this would be good cost effective plan.
I am about 4 hrs south of border in twin city area.
Do you mean "Fluid Film"? It is a very good protectant, and is lanolin based so it is also safe around rubber suspension bushings, fuel lines, parking brake cables, etc.
There are several products like it: Fluid Film, Boeshield (developed by Boeing), Wool Wax, etc.
Note that although these are easy to work with and they do a decent job of protecting metal, they are also rather thin and tend to rinse off throughout the winter. Being thin they penetrate well, and are self-healing, but I was finding rust blooms every spring even when I did avoid snow/salt periods.
Also, applying anything over the top of red, bubbling rust, is not very effective. Iron when it rusts expands tremendously and that creates microscopic pores with huge amounts of surface area for water and oxygen to get in contact in spite of what you'd tried to protect it with.
Optimal strategy (this is what I use):
1) wire brush / needle scale / sand blast off as much red as possible. Cut out badly rusted and weld in new.
2) use a phosphate rinse to convert any remaining minor surface rust to iron phosphate (Ospho is readily available at Ace (pints) and Sherwin Williams (gallons).
3) let that sit and convert for at least 24 hours, then clean real well with a good quality paining surface prep until your micro fiber cloth comes back clean
4) apply 2 heavy coats of the paint of your choice, POR15 is excellent, but as noted above it is not UV stable so you want to apply a top coat over it
5) after the paint has fully dried (at least 24~48 hours) then apply 3 heavy coats of Cavity Wax. There are several brands and all are good. Amsoil HDMP is good, but their applicator nozzle sucks, 3M Cavity wax comes with awesome nozzles, up to 36" long with 360deg spray nozzles for coating inside cavities, Cosmoline also makes tried and true cavity wax. Apply 3 heavy coats if working with aerosol. If using brush on, like Waxoyl, apply it heavy. Note that these waxes are petroleum distillates so they will eat rubber. Be careful not to get them on suspension bushings, wiring, hoses, etc.
6) let the wax dry to a tack free finish. It will hold up for many, many years, but is not self healing and does not penetrate into fissures all that well. So...
7) apply a heavy coat of FF (or the lanolin coating of your choice) over the top of the wax. Plan to touch it up each fall.
I apply the wax and FF outside and let mother nature clean up the overspray from the driveway (saves a ton of masking and cleaning in the garage).
Corrosion prevention is a matter of layers. Each layer protecting the one below, and providing a bonding surface for the one above. They will all fail over time, so more layers gives you more time, especially when working with old metal you can't get perfectly rust free.
Norm "I hate rust" Kerr