...how do I get to know if my rectifier is good needs replacement? Or you reckon carry a spare?
...
I don't know how you can test it but a electrician should.
I have a mechanic and don't do service to my own motorcycle.
Before I leave on a long trip spanning for weeks, I just talk with my mechanic and we do the things we have to do.
I remove everything that has a slight hint of wear (cables, screws).
You can carry a rectifier with you as it's small and doesn't take much space.
I would also advise on having spare (backup) cables already routed besides the default existing ones for clutch and speed.
If a cable should break it's much easier to connect the ends of the spare one, instead of removing the fairings and route a spare. Imagine having to do this at night, on on heavy rain...
Having a air compressor is also a good thing.
And check every bearing because if one of them breaks on the road you will nead heavy and serious tools that are not feasible to carry.
As for tools, I would carry only a small kit enough to just tighten any loose screws on the way.
It's not like you're gonna disassemble the motorcycle on the side of the road.
Also, don't carry oil with you if you can find it on your way. Every middle town should have the oil and filter you need. But check it first.
I mean, you should have a plan before you leave. I would check the map for any options on the way.
If a serious thing should happen you are gonna need a garage and they have all the tools there.
But keep in mind that preparation is the key and doing a serious maintenance before the trip will keep you away from serious trouble.
By the way, I never changed the rectifier since 2015 when I purchased the motorcycle.
Rode in towns at 40°C (104°F), and also at -2°C (28°F) and haven't had any issues. Sure, I had to stop for a few time because of the heat, but no damage or anything that would need a garage or even a tool.
A well maintaned motorcycle will not give you problems as long as you don't crush it.
