I did something similar to mine.
I fitted pneumatic tyres instead of solids, fitted a backpack style 5ltr/min pump (£15) and much lighter than the Sureflo, and a12v 7ah battery (£15) to my PF trolley and chucked the battery box. It's now half the weight and runs all day on a charge. Like you say, at this weight it's a breeze to get in and out of my motor and is much easier to work with as well, because it starts out lighter even with a full barrel and as the barrel empties it becomes lighter quicker. At first I kept thinking I was running out of water only to discover I had half a barrel left.
I also keep spares on board so in the event of breakdown I can replace any part, including the pump within 5 minutes. The batteries won't last like the lithium ones will but at £24 for two they're cheap as chips. The big test will be winter though. So I may be back to the Sureflo with a lithium battery by spring.