Yes, you can use multiple sendable choosers. This
code on github shows working code with multiple SendableChoosers. It also shows how to use non-command types in the choosers. (We use an integer in one of our extras and a boolean in another)
Just in case you aren't aware of auto-boxing (introduced in Java 5), that's what lets you put primitives in an object. Java automatically promotes it to a wrapper object so boolean becomes Boolean automatically.
Feel free to ask questions about the code!