Again, this will vary from DAR to DAR as I've been a part of 3 S-LSA to E-LSA conversions and two DAR's didn't ask for the word light sport to be removed and one did. One of the DAR's that DIDN'T ask for the light sport to be removed works directly for a VERY POPULAR airplane manufacturer in the pacific northwest.
Another Florida member here just did the conversion so we'll wait for him to chime in and see what his DAR said. I was not part of that conversion nor do I know who the DAR was. Although there are only 3 or so of them in Florida.
My
E-LSA aircraft has a "SPECIAL AIRWORTHINESS CERTIFICATE" that is salmon colored and states "experimental" under category/designation. Under "purpose" it reads "operating light sport aircraft-airplane". So my experimental light sport aircraft has a special airworthiness certificate.
As far as placards go, my DAR told me to install all the necessary placards on the plane for "experimental" and put masking tape over them before I flew it to him for inspection. Once he was finished with his inspection I removed the masking tape to reveal the words "experimental" and the placard on the dash for passengers and he was satisfied. Very easy to do if away from your home airport and your hangar.
As for climbing in my plane, the word EXPERIMENTAL is in large 2" letters on a placard that is easily recognizable just as the LIGHT SPORT is on the outside and is easily seen. Then there is a "occupant warning" placard right in front of the passenger that also states that this aircraft is "ametur built" (which it's technically not) and does not comply with federal safety regulations.....etc....etc. No need to hunt down the airworthiness certificate.
We can go back and forth forever on this topic and never get the same answer from various DAR's on the subject. I'm willing to bet money that if you were ramp checked by the FAA tomorrow they wouldn't know the answer to the question either.