Had a sec to think about this more... before you buy anything, are you planning to carry the SL2-S crossbody or just straight off one shoulder? That 50mm Lux combo is roughly 1.6kg which is a lot of static load for a long day. If you want something that actually works well for weight distribution, I've been very happy with the Op/Tech USA Pro Loop Strap 2.5 inch Neoprene. It uses a 6.5mm thick neoprene pad that basically acts as a shock absorber. It cuts the perceived weight down significantly by absorbing the bounce while you walk. If you want a more "Leica" look but with actual padding, the Artisan and Artist ACAM-255A Padded Acrylic Strap is great. It has a 40mm wide padded section that wont slide around like the seatbelt straps do. Both are well under your budget.

Been thinking about your setup for a few hours now and wanted to weigh in. Quick question tho... are you planning to run a dual-camera setup or is it just the SL2-S for the whole gig? If you're carrying a second body on your other shoulder, that changes the ergonomics quite a bit and might make a single strap feel unbalanced. I would suggest being careful with purely aesthetic leather straps for a 10-hour day. I've learned the hard way that looking cool usually ends in a trip to the chiropractor. Here are two I've used that actually work:

• BlackRapid Sport Breathe Camera Strap: This is basically the gold standard for heavy lifting. It's a cross-body design that shifts the weight to your shoulder instead of your neck. It wont look as classic as leather, but for a wedding, comfort is king.
• ONA The Lima Camera Strap: If you need to keep that premium look, this one has a hidden neoprene pad inside the leather. It's way more forgiving than a standard strap but still looks the part. Cost-wise, both are under your 150 buck limit. Just make sure to double-check the attachment points if you go with a sling style... dont want any accidents in the Highlands!

Honestly, that SL2-S and the 50 Lux is a beastly combo for a wedding. I have logged many hours with heavy setups and the strap choice definitely makes or breaks the experience.

• Peak Design Slide Camera Strap Midnight

Specs: 45mm width, internal padding, nylon webbing. The seatbelt material is actually quite stiff which helps with weight distribution. It has a grippy side to prevent sliding, but the edges can feel a bit sharp against the neck after a full day since there is no soft foam.

• Rock n Roll Straps M-Type Cigar Leather Strap

Specs: 43mm width, linked leather construction. This is not just for looks. The links create a flexible chain that moves with your shoulder, basically reducing the shock on your neck when you're walking. It breathes way better than solid leather strips. Personally, I would go with the Rock n Roll for a 10-hour gig. The leather softens up and the weight distribution is surprisingly technical. Just make sure it is long enough for how you carry.

Building on the earlier suggestion, I totally agree that the weight of the Leica SL2-S Mirrorless Camera is no joke after a few hours! I remember doing a wedding in the rain and my neck was just wrecked because I didnt think about the load-bearing aspect. It was amazing how much a secure connection mattered tho... I once had a connector nearly slip and it terrified me! Now I am super paranoid about the lugs and how the strap actually attaches. Reliability is everything when you are on a big gig like that! Quick question tho... are you more worried about the strap material actually failing under that heavy Leica 50mm f/1.4 Summilux-SL ASPH combo or is it strictly the pain factor you are trying to solve? Also, are you gonna be wearing a suit jacket or something with shoulder pads in Scotland? That really changes how the strap material sits and grips!