Man, the X-T5 is such a beast for its size. Honestly, switching from full frame is the best move for your back. I have spent a lot of time testing different rigs over the years and here is what you actually need for Iceland. First off, the L-bracket situation. I have gone through three different ones for my Fuji bodies and the SmallRig L-Bracket for Fujifilm X-T5 4137 is the winner for me. It fits the body like a glove and the side piece actually slides out so you can still plug in your cables. Battery door access is totally clear too, no issues there. It is much cheaper than the boutique brands but the machining is top notch. About the color cast... honestly, it isnt the X-Trans sensor causing that, its just low-quality glass in the filters. If you want neutral colors without spending an hour in Lightroom fixing weird magenta shifts, look at the Kase Wolverine K9 100mm Entry Kit. These things are basically indestructible which is great for Iceland, and the magnetic circular polarizer system is a lifesaver when your fingers are freezing in a gale-force wind. A few other bits to think about:

• Get a physical shutter cable like the Fujifilm RR-100 Remote Release. The app is kinda laggy and when it is freezing out you dont want to be messing with your phone touchscreen.
• Grab a Nitecore FX3 Dual Slot USB Charger. Fuji doesn't give you a standalone charger in the box anymore and you will definitely want to charge two batteries at once overnight at the hotel. You're gonna love the dials on that thing for landscapes. Just makes everything feel more tactile and fun.

@Reply #1 - good point! Stumbled upon this discussion today and figured I would share my experience from a few years back in the Highlands. Iceland is basically a torture test for gear so I tend to be pretty conservative with what I trust. When I moved to the X-T5 I compared a few L-brackets because battery access is a pain if it is not perfect:

• SmallRig L-Bracket for FUJIFILM X-T5 4137 is solid for the price and has a hinged arm for the battery door. It works well enough but feels a bit less premium.
• Kirk L-Bracket for FUJIFILM X-T5 is what I ended up with. Its more expensive but the fit is tighter and it wont wiggle when you are doing long exposures in high winds. For filters, X-Trans isnt the issue so much as the spray from waterfalls. I usually suggest the Haida M10-II Filter Holder Kit because the drop-in CPL is way easier to use when you are wearing gloves. It keeps things simple... honestly simpler is better when you are freezing and just want the shot.

I am literally dealing with the same L-bracket headache right now!! Finding one that doesnt mess with the battery door or the screen articulation on the X-T5 is surprisingly difficult. It is honestly the most annoying part of setting up a new body for landscape work. I have been obsessing over the technical tolerances because I need every millimeter of clearance for those side ports when I am shooting long exposures. Couple quick tips for the Iceland trip:

• Pack at least three Fujifilm NP-W235 Rechargeable Li-Ion Battery units; the 2200mAh capacity is great but the sub-zero wind chill drains them fast.
• Invest in a VisibleDust EZ Sensor Cleaning Kit VDust Plus because the volcanic dust and salt spray are relentless. It is such a fantastic camera tho! I am a huge fan of that 40.2MP X-Trans 5 HR sensor for those massive prints. Tbh finding the right bracket is a nightmare... let me know if you find one that actually works perfectly!

Honestly, Iceland is gonna throw everything at your gear so you really need to prioritize build quality. Since you mentioned being picky about color casts on the X-Trans sensor, I would suggest being very careful with your glass choice. Here are a few reliability-focused bits I would look into:

• The Kirk Enterprise Solutions L-Bracket for Fujifilm X-T5 is probably the most rock-solid option available. It is definitely pricier than the budget brands, but the fit is perfect and it wont budge or block the battery door even when you are wrestling with it in freezing winds.
• For the ND filters, check out the Breakthrough Photography X4 ND 10-Stop Fixed Circular. They are basically famous for having zero color cast, which is huge for Fuji sensors that can sometimes lean a bit purple during long exposures. Fixed circulars are also much easier to handle in the wind than big square plates.
• Make sure you grab a Peak Design Shell Camera Cover Medium. Even though the X-T5 is weather-sealed, the constant mist at places like Skogafoss can eventually find its way into the dials if you are not careful. Better safe than sorry when you are that far from a repair shop.

Facts.