If you wish to accurately measure small currents a clamp on is not the tool to have. I would go with a direct read meter capable of reading up to five or ten amps or so.
I use a ¼ ohm precision resistor and my Fluke to make delicate current measurements. Great for determining current draw on LED’s, fluorescent lights, instrumentation, etc.
I think just about any of the modern solid-state meters are amazingly good, have little loading effect (ohms per volt) and seem to be pretty tough. My old Fluke 10, is now obsolete but has done 20 years of hard service
in much more arduous conditions than a sailboat and is still going strong, but no parts
I have a little radio
shack meter a little bigger than a business card on the boat, just in case the Fluke is not available. It has been there for years now and works great, still running on original battery
. Only complaint is the short leads make some troubleshooting tough, but you should have a couple of jumpers made from good test lead wire with nice little alligator clips no matter what you use as a meter.
If you need to measure big currents get a dedicated amp clamp.
Most of the newer digitals are auto ranging and this can confuse anybody when you are hunting for a result, especially on ohms scale. When it comes up .888 does it clearly tell you that’s ohms or is it K-ohms? You will need to get some experience with the meter before you learn to trust it on auto-ranging scales. Don’t loose the book either!
I agree with foggysail on being able to check frequency. A nice plus if it does that. Your meter does not absolutely have to measure the inverter
output with accuracy. For years I checked the output on a large inverter
with my Fluke 10 and if it measured 91 volts AC I knew the output was perfect and actually acted like 120 volts of true AC.