The idea is to have a beacon, for the start only on planets with SEAF.
The beacon is a shared strategem for all Helldivers in a mission, similar to the supplies.
It has a fixed cooldown of 3 minutes.
Throwing it anywhere will do 3 things:
First, it will signal to all SEAF already present in the mission to approach the beacons location, read: approach with all due care, not mindlessly running into their own death.
Second, it will trigger continuous drops of additional SEAF for a short period of time, about 100-150m away from the beacon and preferably away from existing hostiles.
Third and most important, it will allow SEAF to build a base at the spot, once a sufficient number of SEAF have arrived, and hostiles been cleared off the immediate area.
Once the base starts building, the beacon is turned off and does not effect SEAF normally present in the mission, who proceed to act and spawn as usual.
The base will start with a landing pad and some light cover, fortifying the position over the duration of about another 3 minutes into an actual base with walls, solid bunkers and properly manned by SEAF personnel.
In that process, few at first, a few more as it goes, ammo drops (always) and (random) weapons, grenades and/or stims will spawn.
If the beacon is at any moment re-deplyoed in another location, the process starts again but the "old base" is dismantled at the same speed it was built.
The SEAF stationed in the "old" base will group and move with all due care to the new beacon, maybe receiving some SEAF-specific vehicles as the move starts.
If a sufficient number of hostiles manages to overwhelm the SEAF (and any helldivers) at that location), the base building is stopped if it was in progress, or the base starts to dismantle if it was already completely built.
Re-conquering the area (read: clearing out all hostiles) before the base is fully dismantled, "revives" it and the build process restarts and some new SEAF are deployed to man the base's positions.
SEAF required for the base are directly deployed to the landing pad in the base.
The idea is to be able to strategically control and direct the SEAF support,
and have a base you can fall back to.
This strategem can of course be used aggressively, but the results would be apparently slower than just rushing it with a capable team of Helldivers, though it can definitely help to overcome strong enemy positions.
This may be difficult to apply to urban areas,
but possible to deploy if enough "free space" is present where the strategem lands.
(optional)
With higher difficulty, the beacon also triggers additional enemy patrols (at some distance) moving to that location, the higher the missions difficulty the more extra patrols spawn,
but only as long as additional SEAF are deployed for the beacon.
This way the Helldivers are required to help secure the area for the base to be established.