You can't even bring in one box? I would understand if you tried to bring in several dozen boxes of them.
この場合、次のような言い方ができますよ。
ーYou can't even bring in one box? I would understand if you tried to bring in several dozen boxes of them.
「一箱も持ち込んだらダメなの?何十箱も持ち込もうとするならわかるけど」
to bring in で「持ち込む」
several dozen boxes で「数十箱」
ご参考まで!