I use a multi strand cable that squashes with bolt cutters, and a pretty heavy padlock, feed it through my table, weber, etc .
When away with my boat i use a baby monitor, with receiver next to the bed.
Other option is a flood light ( sensor type ).
Have to be careful with what is visible during the days well , as people wonder past , and see the possibilities!
Sorry to hear about the bike, (insurance ?). As
@BigSkiddy mentioned, report it, as it may turn up. They may frequent parks and get caught, if police know its regular but can only get a pattern if cases are reported.