I'm in Campaign and Rakata gear, and have 400+ presence because of Legacy buffs. My companions have a mix of PvP gear and leftovers from operations. I use Talos to solo Heroic quests and one of the tank companions for standard quests so I can Maul easily. I use Blackout and Legacy Rocket Boots while stealthed to speed up my dailies.
Every Daily Heroic on Belsavis is soloable for me. Old Enemies is very easy and is always a part of my routine. Just stealth, Mind Trap as you run by, and fight the required enemy. I use Heroic Moment to reset Electrocute so I can get extra Mauls in my rotation. I just unlocked Legacy Force Choke, and it's great for any of the major Heroic enemies as well.
The other Belsavis Heroics are trickier because you can not hit the terminals for Lights Out without killing the nearby enemies anymore and you just really need to be careful with your crowd control, defensive cooldown use, and where you place your Death Field. Freeing the Fallen is challenging because of droids generally being able to detect stealth if you have bad timing combined with the patrolling enemies that have some buggy pathing so they are not exactly where they look like they are. Once you reach the final enemies of either of these Heroics, just remember to move from their dangerous abilities. Neither are difficult if you do. I do not do these Heroics regularly because I dislike tiptoeing through trash.
I love the centralized questing in the Black Hole that really cuts down on the running around you have on the other planets. You may not have realized you can solo End of Torvix, should the need arise. Pace yourself and be patient as you Blackout, Force Speed, and Mind Trap your way through the trash. When you reach the enemy with a security key, save Death Field for after the pull to quickly deal with the two medics that spawn. The guard is cake if you handle the healers quickly. Continue carefully dodging enemies and positioning yourself away from packs of droids as you open the security doors. In the final room, spawn the waves of enemies and quickly retreat up the entrance ramp to the hallway. This significantly slows down the rate at which enemies can reach you, and you do NOT want to get charged by everything at once. Liberally use defensive cooldowns, stun & kick. Have a taunt ready if they go for your healer. The waves are easily the hardest part of this instance. Once the robot boss is spawned, you'll find that it does very little damage and Talos can take the knockbacks no problem. From there, it's just a dps race til you get your solo Black Hole Commendations for the week. I had a difficult time getting out undetected since blackout will end when you are in front of the enemies instead of behind them, so I now just Quick Travel back to the base when I've finished.
Ilum's non-heroic dailies are such a cakewalk I see it as too good to pass up, but I dislike soloing Poisonous Strategy because we have less than stellar crowd control for the standard droid packs of enemies, and you need to juggle stuns and kiting while dpsing for the double elite jedi. It's completely possible, but I usually pass since I don't currently need gear from Daily Commendations.
I hope if you hadn't considered trying to solo these quests, you give it a go and bring in substantially more Commendations and reliable credits than if you previously avoided them or had trouble finding groups.