If you are buying as your primary residence, you can do 3-10% down.  

I feel like a lot of the buyers are not looking to buy as primary residence home but as vacation home or rental investment.... meaning vacant home  can have squatters and home are not managed close-by and must use managment company that you can trust but could be un-reliable or reliable. 

If you stick to traditional wholesaling finding motivated sellers can be difficult and it is harder to compete with cash buyers if you must finance. 

Here is my current situation...I have approx $100k in equity in my primary residence.

HELOCs are designed for primary homes.Be prepared to have to call back a few times. 

Just completed a large remodel on my primary residence ($90k in) with the goal of refinancing to consolidate some personal debt and pull some additional cash for other real estate related projects, BUT ran into a road block with a lender.

As one of the larger multi-family lenders in the city, a great deal of my clients are 2-4unit buyers/owners....many of them being primary residence purchases taking the "house-hacking" angle. 

I'm looking to put 5% down (50k) on a multifamily that I plan to move into as my primary.  

Since you have used your VA Loan consider the fact that (and I may be incorrect here) that after 1 year of living in your primary residence you can now utilize the VA loan again if you are moving to a new primary residence.

An odd question, but what would a responsible RE investors consider to be a good % of the value (market price, not equity) of your primary residence compared to their total net worth?