It sounds like you want to build a UPS, the type that protects your computer/server in case there is a power outage.
I prefer one that I can plug into the wall and then when the power goes out. I can plug my laptop/electronics into it.
https://www.homedepot.com/p/Duracell-PowerSource-1800-Watt-Peak-Push-Button-Start-Quiet-Gasless-Portable-Power-Generator-DR660PSS/313518350
A 600W output means that I cant run any kitchen appliance (fridge/toaster/mixer), I cant run a saw or drill. So it is mostly just a jumbo cellphone battery pack that I can use to charge/run my laptop, phone, tv. It can only run some low powered desktop computer. In short it needs an upgrade.
Inverter 15A (120V) = 1800W. With that you can run most household devices/appliances
AC Charger, so that I can plug it into a regular AC wall outlet and charge it
Battery, for lead batteries with 0.25C discharge, I want 4x inverter capacity. So 4Hr x 1800W = 7200WHr, for Lithium that can handle 1C discharge just 1800WHr is okay
Charge Controller this is optional but the midnite kid that you have is perfect
Solar Panel wind and hydro isn't portable unless all you want to charge is a phone, 500W aka two solar panels sounds just about perfect.
But to answer your specific question
Inverter 5A (120V) = 600W. (4hrs runtime from a full battery at max)
AC Charger, missing
Battery, 7x 500WHr= 3500WHr, they are probably old so only at 80% aka 2,800WHr, a BMS is also needed
DC Charge Controller the midnite kid that you have is perfect
Solar Panel the 450W panel is good. 4Hr x 450W = 1800WHr (this will power the inverter for 3hrs if the inverter is running at max)
I think that the weight is good and with a better inverter it would be almost perfect.