Stand-alone HF inverter no-load power consumptions have gotten better than they used to be.
I recently bought an Oubotek 3kW/24V inverter for $220 that only wants 8.5W when doing nothing. Measured with known accurate clamp-on DC ammeter and DVM and calculated by hand. No questionable shunt involved.
For the price, it is a pretty decent piece of hardware. Runs difficult loads like laser printers fine, and starts my Skilsaw. Will be my backup for my "out in the toolies" site if my wonderful 25 yr. old Trace DR1524 ever gives up the ghost. I think the DR will outlive me.