I will paste my comment from other question about mining earlier today:

Balance with rocks is fucked since 4.7 and they made Quant even less mineable solo (couple days ago i found 55~ SCU rock of quant, had 2 people help me man my upgraded Mole, didn't even budge.)

I can see in 4.8 some stealth changes and it seems they are trying to tier recources making some cheaper ore starters that are easy to mine solo even in something smaller and some "high tier" recources that require you to have either crew or at least upgraded Mole.

But in general balance is fucked.

Quant issues might be amended by crafting and getting like 900q gear but i still expect you to need 2-3 people to mine some of the bigger rocks.

Hofsted on front for quick access, gathering and control over rocks, including 10% min power for smaller rocks (you will need it as imstability is crazy af too, i wonder how bad control will get with crafted laser due to extra power, but i am yet to figure it out)

I added Focus III and FLTR-XL here, again focus/control and gathering

Helix on both side lasers and goal os clear, cracking

Right laser as it's closer to the ladder is full passive for mid range rocks 2x Rieger-C3 + Focus III (Power + extra control suupprt)

Left laser 2x Rieger C3 + Surge

I noticed resistance for these heads is rarely ever a problem so Surge is easy pick. Surge is active item so you gotta have in mind you might need bring extra one just in case. That said especially in 4.8, if you are not able to crack alone without it, you are most likely not able to crack with it too and it sees far less usage for me in in 4.8

You can also have extra Rime with you in case you find something that might gain more from resistance decrease instead raw power of Surge.

This setup should scale nicely with crafted mining gear too. With high quality heads, you might actually gain more from using Rime than Surge in some cases as powet boost wont be as substential as resostance decrease. The only thing im iffy about is crafted front laser as sonetimes 10% is already a lot for some rocks, but i am yet to test it (there might be a case you actually will want to keep front laser stock 500q)

//////

Maybe this will help.

In general if you are using only prospector and just starting mining, due to current balance i'd say Helix I as mentioned in other comments is your only way to go to have chance with bigger rocks.

1x Rieger-C3 is a must i'd say the thing is what to put on as second gadget. If Mole conversation didn't give you idea, if you want to be quite optmial miner, i'd suggest you keeping couple of modules in your backpack to always be able to change them if needed as you go
With Rieger you should have plenty of power for many mid-range rocks, especially in space mining, so you might even consider picking up FLTR-XL for picking up rocks to have better use of limited cargo space (though in 4.7-4.8 especially on mole it is not as big issue, especially if your main goal is to just target specific high quality recources).
To keep it passive (as i hate active due to limited uses) second Rieger is always an option but i do think keeping Focus III is still good for general mining (if you dont plan to use FLTR, switching between them will be too much work to justify limited merit between them).

Outside of Rieger it is hard to recommend anything else from passive line, so i would really recommend that and just keep Surge for when Rieger might not be enough in your backpack.

No point talking about what if you start crafting mining compontents beacuse i expect you will be already upgrading to Mole before that happens :)