Originally posted by ags:

The fix is having a backup wildcard portal at your base that you can use for this situation

Exactly this.

At base, setup portals Temp1 and Temp2. When exploring bring materials for 2 portals. When you make a new location build 2 portals, Temp1 and a permanent one for that location. Go back to base using Temp1, make another portal at base for that location. Go through portal for that location. Remove Temp1 at that location.

Temp2 is a continual backup. Worst case if you get stuck; you look around for a dark forest biome near you, get some cores and some fine wood, and make a Temp2 portal.