Depending on your style and placement. Use this limitation as an opportunity to add dimension. in classic style kitchens, the rangehood is central, and the depth of this service cabinet can be up to 500mm, make it wider than the cooktop slightly, then either side install standard depth, 350mm depth overheads with a glazed or panel door, use lighting both under and internally to frame the range hood which will have its own light source, it will centre your focus, add interest and dimension and stylistically, suit the hamptons provincial styles. when doing this, I often suggest the height of these flanking cabinets are also lower as well as slimmer, so then a capping can really frame them. this building of dimension works in both traditional or contemporary kitchens, just make the central cabinet an obvious design element. In modern spaces, it could be a mirrored box, with adjoining timber cabinets, of different proportions. it can work to create a unique and considered design.

I agree with Luke there , some wood can break up large white areas to good effect. We are building a small houseboat too and white will be the dominant back drop to keep things light and airy . Our wooden vanity top in the bathroom ( recycled Tasmanian Oak flooring ) is what we used. The seating was treated in a similar manner. A work in progress. This will be similar to our kitchen area.

Running with your second floor plan (and ignore the glass sliding doors in this image) but would you consider changing your 3m narrow splash to a full sized fixed window on half the side and the remaining side create as the cooking area with cupboards, oven etc.? You mentioned you have stacker doors in the direction of the lounge, but in terms of space, from these doors, it's living area no windows at a room length of around 7m, followed by 4m kitchen room length including a 3m narrow glass splash to provide natural light for the kitchen area (cupboards noted above)? From your drawings there seems to be no windows on the opposite wall, is that right? I feel you will need to bring additional natural light into the kitchen area possibly bigger than the 3m glass panels if only 0.6m tall (or similar) especially with cupboards on top. If you're not keen on swapping out the narrow splash here's another example with your second floor plan (and also ignore glass sliding doors in this image) but possibly a tall window or fixed glass panel before your kitchen bench starts - even if <1m wide. Or greater than 1m if you're OK to encroach on your 3m glass splash and make it shorter. If the island bench is not a "must" you could create similar to this image and have a L-shape bench so it encloses the kitchen a bit more. This will help create the next room of your house ie. Kitchen - and you'll gain a few more cupboards if you're really wanting additional. Then have the big fixed window adjoining the L-shape next to the seating bench. You could still have your narrow glass splash with cupboards above, possibly just shorter (only referencing the L-shape and large door in this image - imagine fixed glass full-size wall panel in lieu of door next to the seats. Ignore the remainder of the kitchen). Is this an existing dwelling or new home build? For either of your options, are you impacting your roof-line as your first floor plan suggests you're widening the kitchen by 1m? The first plan I'm guessing will cost more; light wells and extra bricks vs straight wall. As mentioned by the other posts, there's plenty of storage options. You still have a decent amount of room for cupboards including a full-sized pantry next to your fridge space. I also agree with jbantick's of balancing space indoors and out (not knowing surroundings).

I so agree with Alphen Construction - on first glance, it is definitely the handles that are drawing the eye to changes in height. I would definitely try Alphen Constructions' suggestion re 'blocking out the handles with tape' to see how you like the effect. Take a photo when you do it, you can then compare. I think I would remove the handle from the cupboard over the fridge and the cupboard over the stove. I wonder if a steel extractor fan that would take that cupboard to the same level as the other cupboards might be an effective trick, it would also tie in the steel of the fridge, oven and appliances. Under cabinet lighting is needed in my opinion. I do hope you will be able to enjoy your kitchen because it is lovely. I wish you all the best.