I moved out of California about 4 year ago and sold everything I had there because although the rental would have kept high returns, I didn't trust the laws and lack of landlord rights in liberal states.

However, I would estimate your internet for $100 or less through Comcast (high speed internet only with smart tv apps), $100 for water, and $400 for electric/gas. 

There are some missing pieces of data needed to make an in depth analysis from where we sit and give you more sound advice, however I own/manage property in Tampa which is a highly producing market and:- With $300k to play with you can acquire a $1M property or more which does provide the best cash flow- On a $1M acquisition and $200k (or less down possible) you can achieve 10-30% CoC returns, likely 15% inclusive of management is possible.- Do not forget about appreciation, which is where the real wealth comes from. 

I was turned down for a HELOC with a different lender (a local credit union who would've given me more credit, but determined my current debt-to-income is too high, especially since the rental property isn't generating rent at the moment).I know that I can do a cash-out refi on the rental property in a couple months.

Often times you might consider cashing in like selling high stocks before a crash, but with inventory and housing scarcity in general, I don't think that's the play. 

You'll want to do your own due diligence as the economic environment is changing, but my experiences have been good with several of these highly experienced and  capable fund operators.

:Class A Properties:Cashflow vs Appreciation: Typically, 3-5 years for positive cashflow, but you get highest relative rent & value appreciation.Vacancy Est: Historically 10%, 5% the more recent norm.Tenant Pool: Majority will have FICO scores of 680+, zero evictions in last 7 years.Class B Properties:Cashflow vs Appreciation: Typically, decent amount of relative rent & value appreciation.Vacancy Est: Historically 10%, 5% should be applied only if proper research done to support.Tenant Pool: Majority will have FICO scores of 620-680, some blemishes, but should have no evictions in last 5 yearsClass C Properties:Cashflow vs Appreciation: Typically, high cashflow and at the lower end of relative rent & value appreciation.

I live in BC in the lower mainland, which this market is priced extremely high so I am looking to invest out of province, specifically in Alberta.

Dollar General and Dollar Tree have been building ~1,000 stores each in the U.S. each year for over a decade, and I've read people on the forums who have pursued strategies for building and leasing specifically to these players at a high volume.How is this rate of new builds sustainable, and how can we determine the point of saturation, when the pipeline ends?

Just food for thought are you doing this because you have a high net worth or because you read about it somewhere