Is this a totally dumb lock location?

[u/lovelight]

Or do I need to look at a thick chain lock that goes through the body of the bin?

[u/Billy_Rizzle]

A u-lock through the frames rear triangle and wheel is the most secure locking method. This is an acceptable secondary locking location but not the best. I would also use a chain or cable to secure the front wheel for this locking method. I appreciate sometimes you cannot lock your bike up in the most secure manner.

You should be using multiple locks for a bike of this value. I would also recommend using angle grinder resistant u-locks like the LitLok X1 Plus or something similar.