There are no merits that a vow of poverty provides to this "build". With that said, if you simply must take vow of poverty, take it as early as possible to take advantage of the extra feats provided. (In the build indicated, that suggests that you'll need to take a flaw.)
Druids gain quite a lot of benefit from magic items, even going with the shapeshift alternate class feature. The shapeshift handbook notes:
- You lose all spellcasting abilities while in an alternate form
- You lose all equipment while in an alternate form
- The natural weapons of your assumed forms gain enhancement bonuses equal to 1/4th your Druid level
- The forms you acquire are derived from your base size and improve upon your base attributes
Which reveals the intention behind your question.
First, vow of poverty doesn't interact well: "Also, due to the fact that the forms offer enhancement bonuses to the original stats of the Druid instead of replacing the physical attributes entirely, the Shapeshift variant no longer allows for the Druid to be attribute-independent." fights with the enhancement bonuses given by vow of poverty.
The guide does say:
Vow of Poverty [BoED]:... Vow of Poverty is underpowered at high-levels and this is no exception. Between simple items, such as wands, staves, scrolls and rods of metamagic, you'll be able to buff yourself enough and still be able to get a lot more out of your spells to make Vow of Poverty a less appealing option.
However, it also states:
Therefore, the best way to optimize your equipment is to invest in spellcasting.
Therefore, you'll derive significantly more benefit from buying gear for your spellcaster (especially gear that helps buff spell durations) and inherent bonuses from wishes, than from vow of poverty.
To get high stats in both forms, druid buffs (like bite of the weretiger if you have 11 levels of druid) along with inherent bonuses from purchased wishes will go significantly further than a +8 enhancement bonus from vow of poverty.
Given that you want to make a dedicated melee feral brawler without any emphasis on the half-druid build here, I would recommend investigating the totemist instead, as it may fit your needs better, without requiring the sacrifice of all possessions.