Since vandalism is more of an issue for me then theft I just use a regular lock and focus more on hardening my builds against vandalism. I'm unfortunately subjected to a three prong vandalism attack force consisting of not only the usual malicious mischief get your jollies punks but also cagers who hate me for cycling on "their roads" and will try to mess with my bike, and then the violent vicious "pedal only" crowd that will try to cut the wires to my electric assist or beat my battery pack with a rock or other such similar things.

My main theft issue is not theft of the bike and/or trailer but rather theft of cargo when I've got multiple stops and I'm doing a big haul so I've had to work out methods of locking down access to the cargo areas of my big haulers and cargo trailers. Having six bags or more worth of groceries stolen from the bike while I'm stopping off at another grocery store to pick up more stuff that's on sale at the other store is not an experience I wish to repeat and its a real headache to take the groceries you bought at one store into another grocery store with you and easily get back out of the store without having to show receipts to the management to not have the second store try to make you pay for them again and/or suspect you of trying to pull a fast one and shoplift.

Locking covered cargo boxes and/or trailers and then weaving a length of cable across the tops of open cargo baskets with a padlock on the looped ends of the cable have been the best methods of securing the cargo. I also often use a padlock with the right size shank instead of a pin in my hitch attachment for the lighter weight trailers that use a simple pin hitch set-up like a riding lawn-mower trailer hitch and then for my one custom built towing trike that is built to tow a car type trailer with big ball hitch and electric trailer brake controller I use a car type locking hitch assembly with the locking cross pin on the release for the ball socket on the trailer tongue.

For locking up the bike itself - U-lock, cable lock, chain and padlock - whatever is appropriate for the bike and what I would normally use regular bike or cargo bike, no difference. I do tend to lock up to light poles, sign posts, shoping cart racks, etc. . . rather then the bike rack because usually the bike rack isn't as secure of a thing to lock too and is often tucked out of the way and out of public sight around some dark corner that allows deviants to do their malicious work out of direct public view. It also reduces the possibility of the violent malicious vicious "pedal only" crowd from trying to tear up my bike (why they go after my bike when there is a full parking lot of cars to go after which would logically be the priority target I still haven't figured out and the ones I've caught in the act haven't been able to give me a good answer to that question either even under duress).