You should be able to obtain both achievements from the one save with a little bit of work. you need to pick up one Relic and one Document. The easiest ones I found were those in the right hand corner of the map. With a little bit of climbing and jumping you should reach a ledge with a couple statues and a doorway. Enter here take out the 2 goons and navigate your way to the Relic and Document in this area, not too tricky at all. I will try to upload a GPS file soon but I don't think there is any easy way of tracking what % you have collected and I hope to put up a 75% collection saves if no one else does. Evo is working on All Collectibles and Challenges saves. Feel free to add this to a saveset all I ask for is abit of credit. 25% Cache Save Set a waypoint to the day camp (I think, could be night camp) along the way you will reach a truck the Cache is on the right side of the truck.
Yeah well the all collectibles and challenges save is gonna take a while teddy lol as some of them are a pain in the butt to get too