Hmmm…what would Jared's palace be? And what would be the nature of the distortions within? What would his treasure be, and what form would the final boss take?

I would say his palace would probably take the form of a grand medieval church which he controls as a high priest with good publicity despite the things he does behind the scenes (as a reference to his D&D stuff, with his recording room being the real-life analogue; the scaling wouldn't be the same in the vein of Futaba's palace). The various aspects of the church would refer to his various social media accounts, viewing the faithful (his fans) as clueless parishioners paying him tribute. As high priest, he preaches "gospel" in the form of his videos, but unbeknownst to most, he preys on the vulnerable among the faithful as a vampire, luring them into private spaces (his NSFW tumblr). Cognitive Heidi would be a potential usurper in the clergy he keeps tightly controlled (depending on whether or not he really believed she was abusing him), and Cognitive Holly a "dark priestess" supporting his activities.

The treasure within the palace would take the form of a holy relic proudly displayed but deceptively difficult to steal, while its real life analogue would be his gold subscriber plaque. He would take Madarame's place as embodying Vanity, and the boss fight would be in two phases. In his first phase, as "Father Jared", he would cast Holy-element spells and powerful healing spells, and the "send a character" gimmick would be to position a party member near Cognitive Heidi's cage and taunt him into attacking them, breaking the cage in the process (reflecting how he instigated his own demise with the divorce announcement). Cognitive Heidi would force "Father Jared" into his true form, Jared Azazel Knabenbauer, a vampiric Nosferatu-esque monster using life-draining abilities and Curse-element spells.

Perhaps I'm, uh…taking the comparison too far?