Don't take this too much to heart.....im not an expert....but
You can run a 16ohm cabinet into the 8 ohm jack.
The opposite is not true.......never plug a 4 ohm speaker into the 8 ohm jack.....for example
There may be some people that will argue with me about flyback voltage (or whatever its called) on the output transformer....but Boogies are built pretty tough.......
also, my 50 watt fender bassman is 4 ohms and I use it with an 8 ohm cabinet all the time.
dont quote me, but i think it would apply for the hotplate too.
Your running something with 16ohms of RESISTANCE - therefore being less load, so I dont think its gonna go blow your cab up running half as much signal as you should...
I wouldnt worry about the cabinet with mismatched impedences.....its the Output Transformer that you have to worry about......and then power tubes....and then the power transformer.