Putting a coolant temp sender at ambient temp inline is a way of proving whether this is what is causing your hot start issue - if it starts okay below 70C but not above it........
There are a few issues with hot starting on these, but the cranking speed is number one.
Some engines have updated software, increased battery CCA & the starter upped from 1.7KW to 2.0KW to counteract this fault. To my knowledge only VW supply the 2.0KW starter motor, all aftermarket replacements are 1.7KW.
Therefore to check whether this is your issue, monitor cranking speed & injector activity on a scope with the engine temp above 80C & see what you get etc...