They make clear coats that come in satin/Flat.

If you don't mind starting over, remove the paint down to the metal/plastic, prime with a 1 or 2 component epoxy primer, then a 2 part epoxy or polyurethane top coat.  You used to be able to get 2 part epoxy & polyurethane Chemical Agent Resistant Coating (CARC) military surplus paint off sources on the 'Net, cheap.  Comes in flat, semi gloss and gloss. It was painted on tanks and trucks in Operation Desert Storm, so that if the enemy dropped chemicals or poisons on us, they would wash right off.  I've used it on 2 cars, a truck and a huge trailer. Gasoline, brake fluid and oil won't harm it.  I used to wash the cars with Comet cleanser and that didn't affect it either.  Once you use this, you are done painting the bike for life.  I used to buy it from "Western Resources", but I don't see them on the 'Net anymore.  They sold it by the quart or gallon, and for about $25.00 per gallon, but this was 5 years ago.  Once mixed, you can apply it using the spray kits you can buy cheap at hardware stores.  They consist of a refillable spray bottle and cans of pressured air, and a small spray head attachment.  You pour the paint in the bottle, screw it onto the spay head, screw on the spray canister, and you have an instant spay can of your paint.

If I may suggest, make sure the paint you buy is a 2 part epoxy or polyurethane, and if possible, get the CARC formula.   There are a lot of ads for 'military paint' on the 'Net which are nothing more than plain old enamel colored to look military.

Also, of course wipe the metal down with lacquer thinner or acetone before priming.  Beware of water based metal preps.  Some have Phosphoric acid in them, which leaves a white residue on the metal.  You need to wipe that white dust off with lacquer thinner otherwise it provides a loose surface for the primer to adhere too.  Also, don't use paint thinner to clean the metal.  Today's environmentally friendly paint thinner leaves a microscopic oily residue behind, which is not best for primer adhesion.

Thanks for that, HC.  I've been wondering where to get some more CARC.   I used my last 2 gallons painting 4X4X8 pine fence posts before we set them 2' in the ground.  I did that about 8 years ago with a friend and his posts still look like new with absolutely no rot.  And you are right to warn against the toxicity.  The stuff I used stank bad with a sweet chemical odor, and when I painted his fence posts, his neighbor could smell them for 3 days.

Does the bed liner dry rough or smooth?

the nice part about flat is when it gets scratched just touch it up, you cant see a color difference as long as you use the same can. (did it all last summer.) i was real carefull about filling the tank, used a rag to catch the drips....

dont use high temp flat, it dries almost greyish. i used it on the exhaust only and it looks sweet!

Powdercoat the thing. Porus paint gets eaten by gas ...
Cool.
Srinath.