Linear Drainage Channel

Hello, I'm rennovating some of my driveway and will be installing drainage channel to run into my soakaway.

Now, I can buy corners, to attach complete lengths of channel, but where one channel is cut shorter to fit, the actual fitting 'key' for the corners will no longer exist. Will cutting two to a mitre and sealing with maybe bitumen be alright? Or is there a better way?

Thanks.

Yea just cut a mitre and fill it with some mastic. The channels will be bedded on concrete anyway so there isn't really anywhere for water to escape even if its not 100% watertight.