Mobility, airflow & shade are your friends.

Acclimatisation if time & health allows. It does get easier.

Mindset (acceptance) helps - is essential. With it comes changed patterns of behaviour which aid acclimatisation.

Solar panels or other means to create a 'tropical roof'.

Awnings on all sides to keep the sun off the walls. (Or park in the shade)

Ceiling vent(s) to release trapped hot air,

Van positioning to make best use of available breezes, & electric fan(s) to create breeze where there is none.

Loose cotton clothing like sarongs help a lot with heat & humidity. As does Johnsons Baby powder or Curash talc.

Last resort is to move to cooler & less humid surroundings.