SOLVED. YA fiction/ Spy/ Heist/ Mystery book from the late 2000s -ish. Green and black cover. Girl and boy whose parents got married but then got in some issues? [s]

[Sophia]

I never read it in full so I don’t know what happens, but I think it’s from the preteen boy’s perspective. It’s him and this girl’s parents wedding night or something and they get along fine? She’s in a pink dress but she’s got like combat boots or a camouflage backpack on her too. They slip away to like a trailer or bus or something and that’s when the trouble starts? That’s all I remember.

[Becca]

Pretty sure this is Independence Hall by Roland Smith. The main characters are a boy called Q and a girl called Angela, and at the beginning Angela's dad marries Q's mom. This is how Angela is described:

Angela always carried a small, tattered, camouflage backpack with her. She was carrying it now, slung over her shoulder. It didn't quite go with the long pink dress she was wearing.

[Sophia]

OH YOURE ABSOLUTELY RIGHT THANK YOU SO MUCH THIS HAS HEEN BUGGING ME FOR YEARS