You can do. However, it might be more advisable to transport him in a bucket. This way he gets more room, and is guaranteed enough air. If the drive isn't too long, that might even be a better option than bags. The thing with bags and plecs is that when plecs feel threatend they'll put out their fins. The fins are very spikey on the end and can easily puncture a plastic bag, causing the water to slowly leak out. So if you will use bags, at least double bag him.