Before you make or buy decals do some research on decals on plastic fuel tanks. I learned the hard way. I had decals made for mine and after a few days the bubbles started forming. The decals didn't last long. I think there's vented material that works ok. DEET may know, his looks good.

I believe “speed & sport” makes decals called “wicked tough” made especially for plastic fuel tanks, the plastic fuel tanks “breathe & gas” through the plastic which causes the graphics to fail. Their decals are perforated and have a metal backing, there are some you tube videos on their installation process. I personally don’t have any experience with their products.

IF any of you ferment beverages, then you'll know plastic is permeable... Vapor WILL pass either way through it..
Sneezles61 

You make beer? I like beer. It was 10 - 11 years ago when I learned my lesson about decals on plastic fuel tank. I'm sure there's a lot of new cool stuff now.

The decals and the paint all bubbled on the plastic tank from out-gassing.
But just like bubble wrap, it was fun to pop them!

Wicked tough may be wicked tough or not. I followed all instructions on a YZ400 tank, and they do look good. But, after following all of their installation instructions on a tank that has really never been filled anywhere beyond 1/4 full, the decals still lift. 

Could still be something I did wrong, but just saying...after time didn't stay stuck for me.

Eh, I may forgo the decals. Now I just need to decide on the color of the tank. 

I have a new one here that is yellow.
Never been used.