Going to visit long distance gf for first time, need advice

Hello all,
In July I’m going to be meeting my long distance gf for the first time in person. It’s in Indonesia so it’s going to be VERY hot and humid.

A little about me, I’m 5’11 at 212 pounds so a little bit on the chunkier side. I wear most of my weight on my belly, which sticks out some. That’s where my trouble lies.

My whole life I’ve coasted on graphic tees and cargo shorts. I’m now starting to pivot away from that and go for more polos/oxfords. Chino pants and shorts that don’t go down to my knees

For this trip I’m thinking short sleeve button ups for sure. Shorts are going to be a must.

I’m wondering about what color combos I should go with? I know white shirt, khaki shorts and some clean white shoes would go well. Anything else?

I’m pretty lost in the shoes department. I have one pair of white Vans (upland shoe)

If anyone can direct me where to buy nice shorts and button ups, please do. Would long sleeve with them rolled up work? Do I need an undershirt?

Thank you all in advance