Missions should have a hub and spoke design

1 central mission with several missions spoked off it. Keep your base for all those missions. Drop to same location on all those missions. Missions range from easy to very hard (tech tier 4). When all missions are done you move on to the next hub which is in a new region (same map and can still wander all you like but you move camp to a new region). New region means no base (former base is gone), and you start prospecting a new area of the map. Early missions are much shorter but you don't have to rebuild your base each time. You build up just what you need and done, but next mission you start from there and get to the next tier etc. Short time windows could prevent getting to T4 base in mission 1. Plus since resources re-spawn, they could be the limiter that prevents you from making T4 items in the T1 mission as there isn't enough iron or steel or anything to make all the stuff for T4, but over 8-10 missions there is and more advanced ore could spawn in the later missions.