I think it might depend on how much you need to shrink things, and whether you are set on staying with Nikon.
I don't know what options are still available for DSLR's in micro 4:3. That's a pretty nice compact format, but I think it's dying out as APS-C mirrorless cameras become more prominent. I recall meeting a person sailing off Svalbard using an Olympus, which was so well weather sealed he had no qualms about letting it rain and snow until the thing was soaked. It was practically immersible. His pictures were good too.
If you are set on Nikon and set on a DSLR, rather than mirrorless, the choices are fairly limited, but include the D3xxx, D5xxx, and D7xxx. I had a D3200 for some time, and although this older model is a bit noisy compared to newer ones, it made good images, and was a good companion for world traveling. It's small, light and inexpensive. The kit lenses for this are optically decent, but the lenses aren't very robust and neither camera nor lens is weather sealed. But you can get better lenses. If you don't plan to trade in what you have, something like this might be a good second camera for traveling. I still take the D3200 with a 16-85 lens, when I don't even want to take a camera bag.
One of the big differences here is in viewfinder quality, which may or may not be an issue for you. If you're used to the finder on a full frame camera, the DX size may be disappointing. That on the D3xxx and D5xxx is a pentamirror rather than a proper prism, not as bright, and also not 100 percent coverage. I found the D3200 marginal for careful focusing, and usually used an eyepiece magnifier. The D7xxx has a proper pentaprism, and 100 percent coverage, and the optical quality of the magnifier is not good enough to make it better most of the time.
The other DX model, the D500, has a nice big viewfinder, I hear, and is a pro camera all the way, but I don't think it's measurably smaller or lighter than what you have.
My current ride is a D7100, which like all the D7xxx family is weather sealed and robustly made, and has a lot more buttons and options than the base models. It also makes very good images. The current D7500 is, I think, a little bit smaller, but similar in size, with increased high ISO capability, and might be worth a look.
I currently use the D7100 with the 16-80 lens (silly expensive, but very nice) and the 70-300 FX lens. The DX version of this lens is also good, but lacks switches. The D7500 has software options the D7100 does not, so I went with the slightly better slightly bigger FX version.
My wife has a D7200 with the 18-140 lens, and this is also a nice sharp lens with a good range, though it lacks wider angles. There's little difference between this and the 7100, but it has a better shot buffer and a little better high ISO and a few other minor upgrades.
I don't know what the used and refurb options are, but if my D7100 were to clap out, I think I'd go for the 7200.
Any of these can take AFS and later Nikon F mount lenses with full function. The D7500 will work correctly with any AF lenses including original AF and AFD (it has the focus motor), but the D3500 will not focus anything but AFS and will not meter anything that is not AFG or later. However, they will all accept, and shoot manually with, any Nikon F lens.
I am not entirely sure what you get with the middle D5xxx range these days. It was similar in size and image quality to the D3xxx but has an articulated rear screen, a few more options, more focus points, etc., but comparable sensor.
I think also that D 3500 does not talk to an infrared remote any more. Some older ones did, but I think the D3300 is the last of that line to have both front and rear sensors, and the D3400 has only front. I believe the D7500 also has only front. The D7100 and 7200 have both front and rear. There are other options for remote, including smartphone apps, but I am sorry to see the cheap and reliable infrared fall out of favor.
I almost forgot, also, that the D3xxx and D5xxx models do not offer any AF fine tuning options. If your lens does not focus correctly with the camera, you cannot custom adjust it. I have a couple of lenses with a pretty serious error, and the fine tuning option on the D7100 is a definite plus.
this is all theoretical, of course, because I suspect that if one were realistic and practical about the whole thing, it would make more sense to look at mirrorless options. You get an electronic viewfinder, but it's still a viewfinder, and no focus calibration issues. If you use your old Nikon lenses you need an adapter, but not for the native mounts.
