Based solely on your opening post, and largely ignoring your quest for the ultimate in "natural" I would, if you were standing in front of me and I had my collection at hand, recommend "Royall Lyme of Bermuda's 'Royall Lyme.'"
The product is fairly weak, and in your case that could easily be desirable as it affords you the option of going extremely light with the application. It is a "multi-purpose lotion" indicating that it is usable as an after shave as well as cologne. Simply altering the quantity and location applied will easily alter the relative strength. It has a somewhat limited longevity, and that also could be used to your particular advantage.
If you ignore the ultimate lime "quest" and instead focus on the vast majority of the fragrance's presence it has a very natural, and outdoorsy "flavor" Personally, I get some lime as well as a touch of vetiver. This "outdoorsy" flavor lasts for around five hours, with very limited sillage and little to no intrusion upon those around you. I get the feeling of someone who has been outside working in the yard, perhaps mowing the lawn with a hint of lime added in for good measure. But, and this is a big one, somehow they managed NOT to sweat while doing so.
Originally I am from South Florida, and we, along with the neighbors had many citrus trees in the yard. During the summer, while mowing the lawn(s) I would often pull a lime or two and toss them on the grass. These would often be quite green and not nearly ripened, but when the mower would pass over them an absolutely wonderful, clean and fresh presence would be added to the air. You were already hot, the air was full of that freshly mowed grass smell, and there would also be the stirred up dirt, dust and engine smell. But the mower's smells were easily ignored and mostly you would notice that nice fresh grass smell, and when you added that lime element, well, you could almost forget about all the work and sweating you were doing.
When I first smelled Royall Lyme, I was simply looking for a good lime scent, and it was at best only a so-so fragrance with very short longevity, but it was also familiar somehow, and strangely comforting. After a couple of wears, I began to notice the background vetiver overtones that were present, and began to focus on that particular note. I was astonished at the ability of the fragrance to smell both "dirty" and "clean" at the same time. Then it hit me, I was so comfortable around this scent because it reminded me of my childhood and the little happy memories that could be salvaged from the 90+ degree heat and extreme humidity while doing the chores. That's right, the wonderful smells. I was able to salvage the good without enduring the sweat and exhaustion associated with mowing, especially around and under all those trees.
Perhaps someone else was using an electric mower, the yard had no dust or dirt, but simply only good grass. They used the same lime trick that I used to use, and I was sitting in the shade, with a cool breeze blowing the fragrant grass and lime smell my way. I then went inside and was able to revel in the clean, fresh scents that surrounded and "contaminated" me without having sweat at all. The clean grass and lime scent managed to stay with me for several hours and enabled me to bask in their beauty. This is the overall "feeling" that I get from this fragrance, and I must say that it is an absolute treat to myself to wear it.
I have no idea of how natural the fragrance actually is, and frankly I do not really care. The overall effect is extremely natural, clean, outdoorsy, and happy. That is what I get to enjoy from this fragrance, and although I do wish it would last longer than it does, it has the ability to be re-applied later, or I can simply apply something else for the evening. I have no reservations about subjecting those around me with some overpowering scent that they may not like, and bask in the knowledge that if they actually smell it, they will simply think I have been outside working but without producing any body odor to go along with it.
This can be obtained in rather large bottles for just a little more than a small bottle if you like it, and therefore the cost per application goes way down, making this one almost a steal.
Your stated like of citrus, and vetiver, combined with your limitations of light touch, and natural (well, smelling anyway) lead to recommend that you at least try this one. And I can make that recommendation without any reservations.
Of course, YMMV
I ride a motor scooter most of the time. I get between 80-115 miles to the gallon when I do. On those rare days that I drive my old beater of a car, I get 8 miles to the gallon, YMMV, mine sure does.