IMO, feeding the fish will really not be the consideration. 3 or 4 days without food is not an issue, IMO.
A consideration to me is ammonia versus pH in the fish containers. You have to be testing this. Ammonia becomes less toxic at lower pH. If you suddenly change water you could cause and issue with this by spiking the pH back up.
Temp control. Coolers are nice but they may not really be able to beat the heat. I would consider buying some instant cold or heat packs at the
[hr]
for use inside the coolers if needed. Keep thermometers in those coolers to know the truth.
I personally would keep the rock as mentioned in a container with damp newspaper. I would pack corals in individual containers, as well as fish in individual containers.
Water, IMO, is not so much an issue. You may have to pay attention to mixing it but realistically I have made water pretty quickly and used it without aging at all. So getting that done upon arrival is not so much a concern to me.
Truthfully I would probably just ditch (sell off locally) any sand except for enough to reseed the new tank sand...not sure if you even have sand so may not be a concern. I would just buy new on the other end. It is heavy, takes up space, and is not as critical IMO as other things.
Do you have bioballs in the system at all, or is LR the entire biofilter? Have you contacted hobbyists on "the other end" for assistance upon arrival?
I'm not sure I would bother putting much lighting on anything...it might be less stressful just to "keep them in the dark" lol
I would head over to a bait store just to see what sort of cool things they have to aerate and control parameters in bait systems.
I actually moved FW fish from DC to Houston over several days. I kept them in a cooler (not bagged) and each night was able to hook up a hang on filter to keep the system running well. This is another possible option for your smaller fish...if you have some sort of biomedia (heck even old filter pad or something) from your tank.