At times you can profit $40-50K.

Also included should be the Percentage of Profit Split (after all parties involved are made whole).

That mess is where the profit is.

The return will be lower but he won't have to share it (with me) and will have full control.So why and in which cases would the investor opt for a join venture in which he'll fund the down payment, I do everything and we share the profits?

You pay them their interest rate, and you do not give up your profit. 

Purchased for $75,000 and sold the very same day for $125,000, this deal delivered strong profit with zero rehab and no holding costs.

- Any lessons from moving from short-term profit (flips) to long-term holds with DSCR?

No vertical construction required unless the investor chooses to build later.You can also drop this line into the financials section:Note: Projected profits are based on lot sales only.

Sounds like you will be able to increase your profits well. 

If someone offered to fund the capital but split the profits, would you take a partner on your first deal or go solo and keep full control?