I think it's very good idea. OBD2 scanner and monitor all temps. Much better than shooting arrows in the dark.
I will have the radiator cleaned with pressured air first, It may just be simply too much dirt on radiator so heat is getting trapped in.
It's physics problem I guess :). Law of heat exchange. Hotter weather, the more time engine needs to cool down. Though this car traps engine heat under it's hood. Suppose a design flaw. It's working fine, no indicator etc. so no need to panic (I am panicking
)