Hi there,
I’m a fan of a “Fan” but anything Heatsink related or Free-Air flow is what is required, check to some of the Users suggestions on the other forums too 
, Mr Jenzen’s… jk.
double sided tape , or kapton tape … time to put on the maker helmet and goggles 
heat sink ideas for jetson nano carrier boards - Google Search
check these out 
You can shave one of the passive ones down if you got a machine shop around.
HTH
GL 
PJ 