Short of soaking everything under the hood, you just aren't going to find some vacuum problems with carb cleaner. Oil is another alternative to carb cleaner. The idea is the oil is thick enough to seal the vacuum leak for a short time. This is a good technique if you have found a leak at the top of a manifold gasket by using carb cleaner and it seems a significant leak that you can test for size by using oil. However, oil is difficult to apply in many places and has limited uses.
Propane is probably the best alternative to the above techniques.
A fire is usually short-lived if one occurs and is much less likely. Using one of the available propane tools gives better access to tight places. Always test with the air filter connected to the carb or throttle body to help avoid this problem. Ultrasonic leak detectors can be used with limited success. I bought one when they first came out and was disappointed by the performance.