Your friends are going rag on you no matter what you do. But I suspect if you show up in support of veterans and especially Gold Star parents, your friends will be impressed. Will they still tease you about it. Yep. But lets face it, they know it is an honorable thing you are doing. Just be ready with a response like "I didn't wear the uniform to impress you, I wore it to honor them" and of course, in extreme circumstances, add something like "and your girlfriend thinks I look good in uniform".
In all seriousness, it sounds like the underlying issue may be your own pride as a Scout. While I don't know about your scouting career, I suspect you have done things in scouting that your friends would not have the courage, knowledge, or ability to do. I suspect that you have learned leadership and life skills that will give you confidence to succeed as a young adult. You need to take ownership and pride of that.
Your buddies probably wear a uniform in sports where they maneuver a ball the same way every week. They get really good at manipulating a ball. In your uniform, you are learning to manage the natural world, the social world, and the business world. So tell them to go play with their ball in the corner and leave the uniforms to real men.
Ok, too much? Here is some more practical advice. I assume your friend group includes females. In front of the group, say to a female "I have worked hard to earn the right to wear this uniform and the badges it contains. I have been asked to wear it in school to honor mothers that have lost their children in war. Do you think that is cool or lame?" Some idiot friend of yours will say "Lame", and then face the wrath of the females.
I am writing this as an adult who was not a Scout as a youth. I ragged on every scout friend I had. I teased the hell out of them about their uniforms. At the same time, I was jealous that they were getting to do all kinds of cool stuff.