I have. Easy to make fire & forget survey forces. Just include a conditional for 50% fuel to fuel at nearest location, and survey. Only need to stop them for upgrades and the like.

Which leads me to "Move to Gas Giant with Sorium" and "Move to Mineral Source" (the latter being mainly for NPRs and the former for civilians and NPRs, although they are open to the player). The issue is (in both VB6 and C#) that default orders cause an order to be created when the fleet has no existing orders. However, that means whenever the fleet reaches the target, the default is triggered again (and again, and again). It isn't visible to the player because it is all happening behind the scenes.

Is there a way to make harvester platforms that can lack any significant fuel storage?

Implying their tankers will be directly loading fuel until full, with default orders to do so and the existing conditional to empty at a colony.    An order to "withdraw fuel from harvesters (from parent fleet)" perhaps?

Right now I aim to have fuel harvesters have a years worth of tank capacity and then equally large tankers use a repeating series of normal orders 1)refuel from fleet 2) refuel from target colony 3) unload 90% at target colony.    If I set the speed low enough that all three orders take a year to complete it works to continue forever.  .  .  just tech and orbits mess with it a lot.

Yeah. Could one not issue a 'harvesting' order for working miners/fuel harvesters to keep them from spamming the order?

I almost always use Sorium harvesters with slow engines with the default "Move to Gas Giant with Sorium" and an "unload at nearest colony" condition when full.  This system works well for me and I would hate to see it changed.  Though I guess I could set up the same thing with normal orders on repeat?  Is there a normal "wait till tanks full" order?

I have. Easy to make fire & forget survey forces. Just include a conditional for 50% fuel to fuel at nearest location, and survey. Only need to stop them for upgrades and the like.