It's a pretty important topic, and I was of the opinion that making a new one would cause the ideas hereto to be lost, which was something I didn't want to happen. ^_^
LV, as a mechanic of monsters that upgrade into higher forms, is something that I'd like to see developed on more, agree! The closest custom I've seen (outside of straight "LV" support) is the "Levelution" archetype, where the members were designed to flow into each other, but also had the ability to "add their LV". For example, you could tribute the Lv3 and Lv2 to "Level Up" into the Lv5. This introduces a lot more flexibility, and forms of "alternative progression" like this are something I'd like to see more!
Also, LV is fairly close to Ritual in terms of their weaknesses, but whereas Ritual requires you to have both Monster and Spell (and material), and both Monster and Spell are traditionally bricks on their own, all higher-Level LV monsters are traditionally straight-up bricks in all situations. As such, taking a note from Ritual and giving them alternative hand utility would be a good way to go about improving them!
Of course, one way to do this is to take a page directly from Nekroz and make the higher-Level monsters have Spell/Trap-like effects in the hand. The previously mentioned Levelution's big win condition Level 10 could be discarded to get the Lv1 (and since they couldn't LVUP to the GY easily, this served as a powerful design tool by making players run more copies so they'd always have one in Deck and could use the utility if they drew one- The exact opposite of how
it's status would have normally dictated its usage (to 1 copy).
An alternative was one I tried myself when I tried an LV archetype (sub-archetype?) where the higher-Level monsters had an inherent SS procedure to tribute their lower form, skipping the hoops of meeting your usual LVUP procedure in exchange for going -1 instead of +0 on the summon. This... could use some work since it kinda just upgraded them to the strength of Rituals without an anti-brick effect; Requiring 1 specific card on field and 1 specific card in hand. '^_^
Quickplay Pendulums can't exist, at least not in that way; Pendulums cannot be placed face-down by any circumstances, it's in the comprehensive rules. ;^_^
(Pendulum Monsters) cannot be Set face-down, and you cannot replace a card in the Pendulum Zone with another Pendulum Monster.
That said, Pendulums that place themselves into Pendulum Zone from hand or GY or Extra with a certain trigger would be doable, and actually pretty interesting! >o<
Otherwise, make Pandemoniums. XD