To add to the point above, i'd suggest:

• Kinotehnik LCDVF 3C LCD Viewfinder for sun.
• SmallHD Action 5 Monitor but it'll overheat. i once lost footage when my cam cooked...

Vietnam is gonna be bright as heck so I totally get the EVF anxiety. In my experience, if you're trying to stay under that 7kg limit, a bulky monitor setup is just gonna frustrate you at security and weigh you down on the streets. I've tried many rigs over the years and the Zacuto Z-Finder for Sony FX30/FX3 is basically a lifesaver for this specific camera. It snaps right onto the LCD and gives you that EVF feel without sucking any extra battery juice. Compare that to something like the Portkeys PT6 5.2 Inch 4K HDMI Monitor which is awesome for visibility but then you're lugging around extra NPF batteries and cables. Stick to the loupe for a solo trip, honestly. For power, definitely grab two more Sony NP-FZ100 Rechargeable Lithium-Ion Battery packs. The fan drain is real, especially when it's 90 degrees out and the camera is working overtime to stay cool. I've seen people try third-party batteries to save a few bucks, but they always seem to flake out when the humidity gets high. Not worth the risk when you're halfway across the world. Regarding the handle, the stock Sony XLR one is just too tall and awkward for most small bags. I usually swap to the SmallRig Cage for Sony FX30/FX3 4183 and a low-profile top handle. It makes the camera feel way more solid and easier to shove into a backpack quickly. You'll love the FX30 once you stop trying to make it a full production rig and just let it be a compact powerhouse. Have a killer trip!

Loupes are kinda disappointing in high heat, reminds me of when my car battery died in the middle of a desert trip. We had zero water. Anyway sorry off topic.