Plan what you want to do, in this case Emerald direct to Rewan. Provided you comply with general route requirements, there is no need to fly on an airways route if that route doesn’t actually go where you want it to. This is basically what you do with any plan, direct from the most appropriate enroute waypoint to the aerodrome, it just happens that for most places the enroute waypoint is only 1nm or so from the aerodrome reference (e.g, YBTL DCT TVL) while for Rewan you don’t have such a close convenient waypoint.
If ATC don’t like your plan for some reason, they will query it and you can come up with something else that fits in better with them. In the first instance just plan what you want though. The charter flights for the mining industry do this sort of thing all the time and it is highly unlikely there would be any issue.
When you get to top of descent tell ATC and they will give you traffic if they haven’t already. They won’t know or care if you are VMC or not, that’s up to you to ensure your descent below LSALT complies with the rules.
As for ATC not knowing Rewan, look in the AIP at the user guide for the flight notification form. A departure or destination with no approved 4 letter code should be entered as ZZZZ in item 16 then in item 18 you put “DEST/[lat long]” and “RMK/REWAN”. Now ATC know where Rewan is!