I found a much easier solution, that doesnt require loading different chapters. All you need to do is skiff a little.
Easier area i found...
Red Sand Skiffing Area from UIR Airfield. (Act 3)
Get Talon Relic - at the very start, before you get on Skiff, believe it was left side on plane looking at it from the front, close to outside hangar wall. .
Gnasher Relic - On the north wall of the map... if you go all the way north of the water tower then just slightly east (water tower, all the way north, look for little grey marking on map in sand, or use the relic kills video, find cog symbol and )
Hammerburst Relic - from the transport sitting outside the City Ruins (which is South East of Convoy) follow the wall east-south-east, till you come to the wall(railing/edge of a drop), just to the right you will see a building, get close you'll see the gate is open, there is a body with hammer retro.
Ive included a link to Maka's Guide video just for those people that are getting lost trying to find items and also the timings.
[07:30] - Talon
[08:25] - Gnasher
[11:14] - Hammerburst