I would go with a labbed 30
If you can't swing that much metal try a 28 and work your way down :crossx:
A 20' Pontoon with a 50HP motor is great for Big Bear but when the wind picks up in Havasu you will be running in place. :idea:
You will find this funny but my uncle has a similar set up and I asked him how long it took him to get from Riverland to Roadrunner and his answer was simple and to the point.(He said anywhere from a 12-24 pack depending on how fast the current is moving)
Going with the flow of the water he can get home in about 2 hours.(3 mile ride)