Yes, I will connect 12V gel lead battery between solar panel and invertor.
One 13.7V voltage regilator before battery makes its work in buffer mode.
Its easy, and cheap (solar charger controller cost like 10W module in my post).

Another way - using 5V power bank, but i need 12V for some purposes.

Besides, i experimenting with wind power - its supplements solar energy.
But my area not so windy - average annual is 10feet/second.
It must be composite from Darrie and Savonius rotors.

And great idea use that solar panel on motorcycle - i few times have trouble with generator.
Walking with discharged battery was hard (i have old-syle heavy opposite).