In my experience of fpc/ppc, that connector is fragile.I can confirm there is no mosfet height issue on Lite.
For lcd issue, there is a big metal (yes metal so it can function as a mosfet heatsink if any) frame that separate the board and the lcd unit, so no issue.
My main enemy for this to be easier is this lcd flex connector, its hard to reattach at least for me.
And for Lite this method of instalation will take more time than the default SOC solder.
For thermal paste i say if the unit is new then just leave it as this will also make the soc header cover still in perfect condition.
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Do not take it off using nail. That is the most common mistakes people do.
I bought cheap spudger for that. Use the appropriate tool was always the answer.
And luckily nintendo use a more rigid one for the lcd connector.
I don't think the mosfet even heat a little bit.
The high charge only flows in a range of microseconds (not continuous), and that also only in the boot process.
If heat is an issue, the lcd create ways more heat than the mosfet.
Also the lcd and cpu is the part that use the most batteries energy.