Hi Warren and welcome!
FWIW I would suggest not modifying the unit until after you have done the course. Get a feel for the unit as it was designed, understand why things are done the way they are, then start changing things if you still feel the need. I have certainly changed my unit extensively, but to make it heavier not lighter as I don't like carrying a weight belt. I have also swapped over to a harness and plate and a different wing but each modification has been for a specific reason - clipping stages, trim etc.
Also, I know that there was a change in the bucket size after my unit, but three hours seems extraordinarily short duration on your scrubber - I run mine for six - one pound per hour is the general rule (taking into account conditions etc).
Enjoy your unit and you never know - maybe those under water destinations overseas will look a whole lot more appealing!
Cheers,
Ben.