I would minimum do the .22 cent mod #1, just doing this will really help your engine not try to burn itself down.
I would suggest that the doohickey update is more important than a thermo bob. The thermo bob is more of an improvement than a MUST.
(even with a thermo bob your temp will rise in heavy traffic, it just doesn't fall as far or as fast, the thermo bob changes the thermostat from a 160 to 195 degree) and then keeps the temp there. In traffic the fan WILL come on. It is very quiet and you may not notice it, but it SHOULD come on.
If you want to cheat for now, drill a 1/16th hole in the outer ring of the stock thermostat (inside the sealing area). Then position that to the top during installation. This will help keep the coolant moving as that is a major problem with the cooling system is the hot spots due to the lack of coolant movement around the thermostat and then the rapid drop in temp when the thermostat finally opens.
I did the pro cycle by pass kit then necked down the elbow for the by pass to a 2 mm bypass instead of 1/4 ", my temp needle is rock solid even in the cool weather up here in Canada. I can even tell when the engine case is up to temp not just the cylinder and head. I also did the Mod MY WAY and didn't even have to remove the fuel tank or one shroud and it only took about .5 hrs and i don't have a big external thermostat housing hovering close to the radiator fan being held back by a ny tie under the fuel tank ....
Oh, i put the thermo bob2 thermostat (195 deg) in my modified pro cycle by pass (180 degree) ... going to hell for sure .
And for all you nay sayers out ther (westman lol), the air bled out fine even with the hose routed under the front engine mount, and the by pass hose running past the exhaust hasnt been an issue (high grade silicon hose). Was going to use some adhesive foil on it but doesn't seem to be an issue at all.
Man i need to update the stock skid plate, already got the low pro drain plug. Lady you need the EM low pro drain plug if you like to skip over stuff.
It's been fine. Heats up a tad when stopped at a light or whatever but from my readings, appears that KLRs run warm. A thermo-bob is my next mod planned!