So I'm finally getting close to painting my 68 Mustang. I stripped the entire car to bare metal all the way around. I then sprayed everything with Epoxy Primer. The engine bay I plan to BC/CC in a satin black. Should I do the same to the back side of the fenders, floor pans, and wheel wells or just leave them in black epoxy primer, or is it best to spray a rubberized undercoating on these areas. I plan to just use it as a summer weekend show car / cruiser. Whats the right way / industry standard for these areas and what products are best for these areas?

Thanks for the advice ~ Lenny B

Anything that won't see sunlight can be left in epoxy. Any type of undercoating is prone to trapping moisture. Unless you were looking some kind of sound deadening improvement, I,d leave it alone.

I use a product called DEI BoomMat; it's waterproof, non chipping, and does
a good job of soundproofing road noise. Comes in aerosol cans and a can will
cover one car's wheelwells.

Floor pans are another matter, and up to you. Some like to undercoat, some don't...

If you plan to show the car more often then not Undersides are Painted in Body color and Protective coating applied over that such as The Mopar restorations I am involved with.

In the case of My Firebird the interior was originally left in the Red Oxide primer but the bottom side of the floors were covered in a Black paint coating while other Pontiac's I have witnessed restorations of the bottom of the car floor was left in the Red oxide copying what the factory did and anti corrosion under coatings applied over that.

My Point being If you plan to show the car You need to decide on what Class you intend to show it in? STOCK, Modified stock or Modified? the classes get silly in there naming after that but there are many different category's to show your car in.
Car shows are very competitive in there different classes. just depends on what you wanna do and how serious you want to be? the Modified classes of competition are by far the biggest classes and generally the most laid back and most fun in my opinion guys generally aren't to serious about winning its more about the different cars and having fun with the attitude that every one should come bring there car or projects and join in the show and have fun, BUT can be very serious depending on the level of the show.

The Original classes are generally more serious especially for Restorers and guys that detail cars.

Did you have to remove undercoating when stripping the car?
I believe most of them came with factory undercoating but like Dennis points out it really depends on your ultimate goal in restoring the car.

I used U-pol Raptor bed liner on the inside and outside of this 1967 Jeep CJ7 (in projects section) and it still looks great today. Sprayed it directly over epoxy primer.

Just my opinion, in building custom cars for the road. I like to use either POR-15, if the undercarriage wasn't completely cleaned of rust, or epoxy primer, if it was. Then a coating of a catalyzed bedliner. Looks like undercoat, but better. Holds up very well over a lot of mileage.