Hi, YES, Rustoleum "metal" paint comes in white! The METAL PRIMER is one of those "rusty" colors, but the PAINT -- well, you probably have fifteen choices or more, AND you can mix colors.
Rustoleum MARINE paint (more flexible, even, than the metal paint) comes in more limited colors, and good luck finding more than a couple in stock. But WHITE is one of them! And the MARINE PRIMER IS WHITE (slightly warmer than snow-white).
AND you can mix the marine paint as well (I e-mailed the company and asked). YES. BUT if you go outside of the premixed colors, you'll play merry "heck" matching it again later, so measure carefully.
On Shelly, the little motorcycle cargo trailer we used as a learning experience for fiberglass, we put two coats straight Rustoleum MARINE white on the top half, over a very thin coat of marine primer, also white. For the bottom half, I mixed leftover paint we already had: some "safety blue" Rustoleum metal paint, some Rustoleum metals paint black, and a big blob of Rustoleum white metal paint. It turned a very nice cadet
blue (slightly gray blue, mid-tone) and we used it inside and on the outside bottom. I have GOT to get some photos of it up.)
(Shelly will have to be completely repainted should we ever need to patch her, we'll never match that exact leftover paint mix.) But that's OK for now!
Two coats of the Rustoleum metal paint and it was good to go. Again, Paul only rolled it, he didn't roll and tip. The top he only rolled, as well, as the MARINE paint self-levelled very nicely.
It's NOT super-shiny, but has a classy kind of dim sheen.
It DOES look like what it is, "fiberglass," not unlike a BOAT, and we've had a LOT of compliments on it already.
PREP is very important...sanding with a proper grit (Paul used 100 for a first sand, and 1000 between coats). Then he wiped it down with acetone and let it dry (fast).
Shelly is small enough he did it all inside the garage. the bigger trailer he's done some tarping to work on it even in the rain...we're not sure quite how we'll do the final paint, possibly he can roll it into the warehouse where he used to work for a weekend--that'd probably do it.
TWO coats of Rustoleum MARINE paint was plenty...we used about 1/2 of a quart on the top half of Shelly for both coats. we barely used any of the primer, as we kept it super thin (Shelly was dark blue when we got her...actually I thought of Shelly as a "boy" trailer, she was all kind of Hell's Angels looking, so now she must be transgendered.)