How I've dealt with my red HOV stickers (haven't had time to place the sides yet), which I feel didn't come out horrible. I kinda planned early for the red HOV stickers and figured I needed to tie the color into the car. I did this by getting the front and rear Tesla decal wrapped in red as well as sticking red decals on the aeros. The results are below.
The decal for the front actually worked pretty well with the way the bumper is shaped under the light. For the rear I just lined up the horizontal line of the bumper and gave a little bit of spacing from the red reflector to avoid a noticeable clutter.
I think for previous examples in the thread...some of you really need to work on lining up the angles. Yeesh. Forgot where I saw it but I sprayed a mix of 1:5 ratio alcohol/water from a spray bottle to mist the bumper and sticker before applying so that I could move them around and check positions. That helped tremendously.