Alright check this out. I'm like you and I need too get my last faction to 75 and it's reapers and don't want all that heat.
Spawning in check the map for a reaper hopefully there is none or it's busy at an event or something you know what to look for.
Raise the merchant alliance flag and buy all the commodities. Lower the flag immediately. Collect the commodities there should be about fifteen.
If they have a cargo mission pick it up and put it down you should be able to pick up the cargo at the same outpost except for the Devils roar witch has its own thing going on. If you put down another it will be close and you can get those to.
Go to the next outpost and do the same.
After the third outpost take all your cargo and commodities and go to the reapers hide out. Make sure nobody is around. Raise the reaper flag and start selling. After a little bit you will start to get multipliers and some rep. After your done selling lower the flag. When selling just keep an eye on the map and horizon.
Rines and repeat.
You will run out of cargo missions and commodities eventual then it is time to move to a new server. This way your only a reaper when you sell and a emissary when you by commodities. I play solo and understand the struggle. I saw this on a video and it works great. Especially during double gold weekends. Just remember to keep those flags down and keep moving because those reapers like to reap.
Even if you get caught at the hide out and sold most your loot you will come out way ahead .
Hope this helps you become a legend. Yaaarr.