Yes.
I will start by explaining my point of view on promotion because i typed my answer and realised i should explain why it's my answer
Level 20 was significant when i played, the average level was below 20 and very few people were above 40 with the top levels still under 70. (Nebula 7.2-7.6).
20k was a lot of money back then, it was not uncommon to see premium players over lvl 20 without promotion. The average player did not have 20k by the time they were lvl 20
Tibia was hard so the increased regen made a significant difference to hunting, it's a good reward
The spells were really cool and significant
Tibia was a simple game and promotion was simple too, not locked behind anything silly and not tedious.
A second promotion should feel the same way in my opinion
It should not be too low of a level so that it's easy but should not be out of reach.
The cost should be significant and not affordable by merely playing the game casually until you hit the promotion level, there must be some effort... remember lootbags?
It should introduce new ways of hunting, either through content, spells, regen etc doesn't matter.
Your character should be more fun and efficient afterwards.
It should not require anything tedious to get.
I am also working on a low rate project and plan to have a second (and maybe more) promotion. It will probably be lvl 100 and cost ~400k with a semi-rare item related to the current vocation. It will boost hp/mana regen, won't touch exp loss and will unlock new spells which will mostly be upgraded support spells such as a large area challenge, faster and/or longer lasting hastes etc
Of course this needs balancing against your specific rates. I chose 400k because lvl 100 will not be easy, 14 days+ of active playing (so about a month on average) by which time 400k should be well within grasp for those who try.
I've read your thoughts above and it seems like you have some really good ideas, good luck (Y)