Thanks, guys! I was aware of the inverters. The places I had in mind (attractive spots in public parks) wouldn't allow for me to bring the vehicle so I thought I could use an inverter with the marine battery as a last resort. Even if I had to bring it out there with a hand truck. I also still have several
battery belts around from when I used to do weddings... though I'd likely have to replace the cells.
A mixer would likely only draw 22-40 watts and I probably need no more than an hour run time.
So I was really hoping that there was some device out there that was all-in-one and "carryable" as opposed to the inverter/50lb battery combo.
Let me check into the jump boxes. My understanding was that they were designed for a quick, high-energy release and not so good at running a lower-power item for a length of time.