I'm not clear if you want to find pre-made signs with the image of a FGRV on them or if you are looking for images to make your own sign.
One problem I've found with Googling "trailer" is that the word in confused with a movie trailer. Suggestion: Google "camper trailer road sign" and click on "images". Also look up "camper trailer icon". You will find a ton of images. Go to the Cafe Press website and look up "trailer" and you will see images galore that can be purchased on all kinds of products. Our own FGRV has a "Store" tab on the top of the home page. Click on it and you will see the FGRV logo available on Cafe Press products!
The RV camping roadsigns in California have an image of a small fiberglass trailer. If camping is limited to tent camping there is an image of a tent. These may be universal icons throughout the states, I just don't remember.
'Hope these tips help!
The Gleeful Glamper
"Here we go again on another amazing adventure"