I didn't have any problems with spellpoints on Lamannia and i was certainly not optimally geared. Of course if you have to cast all the resist spells instead of using ship buffs that is not very spellpoint effective but still. And also Spellsword is only one spellpoint every 6 seconds that you fight so only 60 spellpoints per minute of continuous fighting.
I always used extended buffs so they last 22 minutes and only cost 10 more spellpoints. They will easily carry you to the next shrine whereas recasting them would drain far more spellpoints. You can also start Tenser's in a public area and regain the spellpoints there and it will still be active inside quests and even last through rest shrines so you can save spellpoints there too. The only thing you really have to spend spellpoints on during quests are extended Displacement and Reconstruct and if you kite and evade mobs, use safe spots and far range to your advantage and keep Displacement up during a fight that should not be needed too often. Displacement is 2:12 minutes for 30 spellpoints and quickened Reconstruct is 45 spellpoints per use. You should have repair spellpower in your gear setup to make every reconstruct spell count and of course a high INT and repair skill help with that too. Quickened lower level Repair spells are far less spellpoint effective than Reconstruct by the way. You should not need cocoon at all since you will take a lot less healing from it than fleshies do.
If you need to save more spellpoints you can cast GH, True Seeing, Reconstruct, Resists, Stoneskin and Blur from scrolls or wands or use clickies with GH, Stoneskin, Jump and other buffs. Haste is only needed if you took Epic Reflexes and want the running speed, Fire Shield is only needed if you encounter heavy elemental damage and Rage is not needed at all if you are not running in a group since you will only benefit from the few temporary HP. If you cast Reconstruct from scrolls between fights very often it may be useful to shift some AP in the eldritch knight tree to Wand and Scroll mastery.
To help with healing the Tier 3 Epic Ring of Master Artifice from House C challenges is a good thing to start with. It even has Archmagi, Greater Auto-Repair, a free Reconstruct clickie and HP regeneration on it. In endgame you would switch to a Thunderforged Shortsword with repair spellpower, repair crit and armor piercing in your offhand or you can slot repair spellpower into your Thunderforged Shuriken if you want to use Celestia or Rebellion. If you feel like you have to heal yourself too often maybe you can still improve your defenses too.
To regain some spellpoints per rest you can use the Archivists necklace from korthos, the Spellstoring Ring and the Twisted Talisman if you don't have a Bauble yet. Also you can wear a GS conc opp item and a Torc in lower levels. If you cannot find a gearslot for a high spellpoint item you can switch one in before you enter a quest and switch it out after buffing. That works pretty well with a blue planar focus when you have Celestia in the offhand.
If your spellpoint consumption is still too high even after taking the above things into account you can always switch to the variant with Mental Toughness, Improved Mental Toughness and Epic Mental Toughness that i described in the OP but i really don't think that should be necessary.