Cargo Bikes

a lot of cargoes have these https://www.dutchbikebits.com/axa-defender-wheel-lock for easy lockout of the rear wheel. that and a kryto/hiplok chain will sort you out

I guess weight isn't really an issue with a cargo bike that already weighs loads so maybe you wouldn't even notice a beefy chain that much? Might give you more options for where you can lock up. We actually don't lock the Bullitts we use ever but that's in Leeds, we only leave them unattended for a few minutes at a time in busy areas and they do occasionally go missing so I wouldn't reccomend it!

@mdle We have a Douze and at almost 4K fully loaded I just don't want to risk losing it, especially as we are highly reliant on it for our daily routine of dropping off nipper/commuting.

Lock wise we have an Abus Bordo X Granite that goes through the front sub-frame and front wheel (expensive to replace due to dyno hub) and then a motorcycle chain for the rear wheel/frame enabling us to secure the bike to something immovable. The chain sits behind the seat base when in use and we use a bungee cord to help hold the seat in it's folded position when not in use as the lock is slightly in the way. I put old mtb inner tubes over the chain links and also store it inside a cut-off leg from a wet suit, this seems to keep the noise down, otherwise it'll rattle like a bastard...

Locking to stands is fine, although if bike stands are rammed, it's hard to fit a cargo bike in at times, plus I get concerned over other cyclist gouging the windows on the canopy with their handlebars etc. The motorcycle chain is a Thatcham rated English Chains lock which was my wife's motorbike lock from a few years ago. It's pretty light for a motorcycle chain, but the extra length allows us to use lamposts to secure the bike to and lets us put helmet straps through it if we're at a park and don't want to carry stuff around with us.

The bike was locked up outside for a whole year in the Chiswick area where I worked until they finally finished the secure bike parking in my work. Nothing happened to the bike during this time, but was never happy with it being outside like that in all weathers and I worked quite a few late nights so bike was left from 08:30 to about 03:00 at times.

Be aware that those Abus Bordo locks are not as big/user friendly as they look and you'll struggle to get it around both wheel, frame and immovable object.

Finally, it's really worth test riding cargo bikes. They are all very different in style/the way the ride and none of them cheap... but they will always leave you with a big grin on your face :)