Commercially speaking, most developments are prepared using a company (or a trust with a corporate trustee) in the event that some sort of claim for building defects comes up in the future, the claim is limited to the company and stops there (unless they find a way to sue you personally). The big problem is that since the land is in one entity, the end product will be in the same entity as well.
This is how I would do it.
1. Set up 2 trusts (sell trust, rent trust) with 2 different corporate trustees. Buy the land in the rent trust.
2. Subdivide the land, then transfer the land you intend to sell into the sell trust. The sell trust pay transfer duty on acquiring them.
(which will increase the cost base for the eventual sale. The rent trust may incur a capital gain/income to declare in itself on the value of the property transferred less purchase costs and subdivision costs. This should not matter since we are merely declaring a gain that would have been earned in the sell trust anyway).
3. Build the houses. See your accountant for tax treatment and the allocation of debt.
4. Sell the houses in the sell trust. The rent trust may have some losses that you can distribute to it to offset some of the profit (since it can claim interest, rates, etc during the construction phase - make sure with your accountant/lawyer that you can do this). Of the sale proceeds, ensure that you pay off the debt related to the property costs of the sell trust (unless you don't have the capacity to repay it - again see your accountant).
I would recommend paying the transfer duty on transferring the subdivided land prior to the build as other options would be more costly. SA stamp duty on a say $450,000 transfer (if that was the value of the land after subdivision but prior to construction) would be $14,093. Setting up a joint venture to distribute the output (ie houses) would cost you all up at least $15,000 in fees that you may not be able to claim all of and if you are selling the properties in the sell trust, it makes no difference at the end of the day.
You could buy the land in your own name, and then transfer the land after subdivision to just one trust, but that depends on whether the properties will be negatively geared after construction. I would be tempted to.