Omg you're gonna LOVE Iceland!! My trip last year was awesome but the wind was seriously insane, like it'll literally knock you over. I had that exact same sagging issue when I used my Sony E 18-105mm f/4 G OSS lens because its kinda long for the a6400 body. It creates a weird center of gravity that cheap heads just cant handle. I ended up getting the Vanguard VEO 3GO 235AB Aluminum Travel Tripod and it was a total game changer for me!! The 23mm leg diameter makes it feel way more stable than those super skinny ones. The ball head is way more solid than the K&F ones, basically zero creeping. I also looked at the Sirui T-005X Aluminum Tripod with C-10S Ball Head which is super light, but the Vanguard felt beefier for the wind. Just make sure you hang your backpack on the hook at the bottom for extra stability. You're gonna have such an amazing time!

Regarding what #2 said about "Building on the earlier suggestion, I've had a..." rough time with the Manfrotto, I totally feel that. Those tiny ball heads are just a recipe for disaster with the 18-105mm lens because it's so front-heavy. So basically, the consensus here is that Iceland is windy as heck and you need a better head than the basic travel ones. I stumbled upon this thread today and had to jump in because I've been extremely satisfied with the Sirui T-005S Aluminum Tripod with B-00K Ball Head. It's been my workhorse for a year and I've had no complaints at all.

• It folds down to like 12 inches which is insane for carry-on.
• The weight hook on the center column is a lifesaver for stability.
• It's way sturdier than the K&F or the cheaper Manfrotto models. I took mine out to the coast during a storm last winter and hung my camera bag from the hook. It didn't move an inch. Honestly, for about $130, you arent gonna find a better balance of portability and strength. Just make sure you really crank down the plate on the camera body tho... that lens likes to twist if you arent careful.

Building on the earlier suggestion, I've had a pretty rough time with some of those entry-level name brands. I actually tried the Manfrotto Element you mentioned and honestly it was a total letdown. The ball head is just way too small for that Sony E 18-105mm f/4 G OSS lens. Every time I thought I had it locked, it would just slowly droop. It's super frustrating when you're trying to line up a shot and the gear just won't hold. Iceland is honestly the ultimate test for tripods. I learned the hard way that cheap plastic leg locks will actually snap in the freezing cold. I've had much better luck with slightly more specialized brands that focus on travel gear specifically.

• Benro Slim Carbon Fiber Lightweight Tripod is probably your best bet under $150. It is way stiffer than those cheap K&F options and handles the front-heavy a6400 setup much better.
• Sirui T-025SK Carbon Fiber Travel Tripod with B-00K Ball Head is usually right at your budget limit. It is tiny enough for a carry-on but surprisingly rigid for the size.
• Vanguard VEO 3GO 235AB Aluminum Travel Tripod is a solid choice if you dont mind the extra weight. Tbh, if you buy another super cheap tripod, you're just gonna be buying a third one in six months. Just make sure whatever you get has a hook on the bottom to hang your bag... you'll definitely need that extra weight to keep it from tipping over in those Iceland gusts.