Bounties can be profitable at all points in the game, but you need to have an efficient fleet and good skills and officers. If you just drag around a bunch of average ships with a bunch of QOL skills, you will struggle. The key part is to win with minimum deployment cost (try to deploy and use as few ships as possible while still winning). The extension of that concept is that you only want to use ships that have good 'combat power per DP', so there are lots of ships that are simply not worth using because they are too weak to be worth their upkeep and liability of damage/loss in battle. There are still lots of viable combat styles that can reliably beat human bounty fleets though. The skill that gives bonus cargo/fuel space is also very nice for keeping a slim fleet with good enough cargo capacity.
There's also definitely a transition point where you need to get a lot stronger to continue hunting bounties which can be tough. Early on, you get the <150k bounties that can be handled with only frigates and destroyers, but you will hit a point where you suddenly start seeing much larger fleets and lots of cruisers and capital ships, and you need to scale up quickly to handle that. In terms of specific fleet compositions, I'm not too experienced with pure low tech fleets (I usually mix and match), but I know that onslaughts are very strong and dominators make an acceptable substitute early on. Also, missiles are a key part of low tech combat power (kinetic guns with lots of harpoons is one good idea), and carriers/fighters can be used to deal with small flanking ships (I prefer wolfpack frigates, but pure low tech doesn't have great frigates for that in the late game). Also, skills make a pretty big impact, so I think it's important to pay attention to your officers and not settle for mediocre pod officers because they are free.
It will also be harder if you are restricting yourself to a subset of bounties by not taking them from certain factions. I've never tried that so I don't know how much that would affect you.
Exploration profits are much more about salvage than the quests (which are pretty trivial by late game). You will find lots of rare stuff and resources that you can sell (just remember to save whatever items and blueprints you want for colonies). AI cores can also be turned in for good profit. I would also say it's important to get your surveying abilities to a point where you can survey all worlds for 5 supplies (sticking the hull mod on civilian ships usually gets me there, and I think the one of the industry skills helps as well). Then you can survey everything and sell the data for extra cash as well and you will also find lots of ruins with more goodies. A last point is to remember that basic resources (metal, food, organics, ore) sell for very little. IMO it's really not worth trying to be able handle the huge drops of those you can find, you're better off just dumping them for better stuff and keeping your fleet slim rather than lugging around 8 atlases incase you find 10k + ore lol.
Personally, I mix those two strategies, and go do 1-2 bounties in an area before exploring the nearby systems to gather whatever goodies I can find to sell. I end up with a fleet that isn't necessarily optimized for either exploration or combat (definitely combat leaning), but I make plenty of money.
