Mujitsu and Tairaku's Shakuhachi BBQ

Greetings everyone. I have a bit of a problem at hand. In a couple of months I need to attend to a wedding. My girlfriend's sister is getting married and naturally we are invited. There is quite a bit into the story but the short version is that we were asked to play shakuhachi and sing there and they sort of asked if it would be possible for us to dress in japanese style to add to the effect.

Since I know that we have members here on the forum who either live in Japan or have attended to weddings there I wanted to ask if anyone could let me know what the proper combination of clothing would be? This is hardly a matter of life and death because nobody but me will know the difference. I would still prefer to get it right even if just so that I'll know if I ever need to do it again. I was thinking of going with hakama, kimono and a haori on top of that. I also thought of having both the hakama and kimono in black and with a colored haori. It'll be outside event and during the summer which means that some nice color could perhaps work nicely. Would that sort of thing be completely unacceptable and if so, what would you suggest?

Thank you for any advice.