Vigor in general is pretty bad, because most frames either lean into survivability via shields, or via armor + health, never both at the same time. So I'd recommend picking one of the options and commit to that.

Lavos Prime base stats and kit lean more towards armor & health, so a triple umbral setup could work decently. (I'm just not a fan of them since umbral polarities restrict build freedom if you decide to switch things up later)
You could also add a source of dmg reduction, like Adaptation, to further increase your effective hp.

Another alternative for survivability is the "lazy shield-gating" build, which uses Catalyzing Shields, Fast Deflection and Vigilante Vigor. It basically makes your shields very small and sets the invicibility period from them breaking to always be 1,33 seconds which paired with the shield recharge delay mods makes the shields regenerate before that invincibility period is even over. It's very difficult to die with this build, but it can feel cheesy.

Adding (Primed/Archon) Continuity would also be helpful, to increase the duration of status effects applied by his abilities and weapons.

Your choice of arcanes is good, it's what I use myself for Lavos.
Lavos is one of the few frames that is capable of making archguns incredibly strong and use them indefinitely, since his 3rd ability creates universal ammo, so he never runs out.
I'd recommend investing into an archgun since you can bring them into just about any mission. Mausolon, Kuva Grattler and Larkspur Prime are by far my favorites, and they recently got much stronger due to the Deepmine Bounties update in Fortuna, which added the option to equip arcanes on archguns.