The biggest constraint on these communities is financing rate uncertainty.

A deal could look good at 7% interest rate with 25% down, but underperform at 7.5% and 30% down. 

I vividly remember the countless hours spent driving to and from remote locations in rural Manitoba, alternating between early BP podcasts and Jim Rohn recordings.Over the next two years, I adopted an extremely frugal lifestyle, enabling me to achieve a 75% savings rate, sold my custom truck for a used Toyota, traded my new home in the burbs for a duplex (house-hack) in a challenging neighbourhood of Winnipeg where attempted break-ins were commonplace.

He would be safer in a savings account at that rate (I know what you're thinking... appreciation, though).

Assume a 10% (pulled out of the air number) interest rate on the heloc.

They also claim that their property management fee is 10%, which is true as long as the unit is occupied, but if you factor in the first month rent payment for placing a tenant and a 5% vacancy rate (about once every two years) then the property management fee is closer to 15%. 

Im thinking of renting out my primary which will cashflow $650 (no management fee, self manage) because of low interest rate i got it for 2% which still has 2 years before rates renew. 

Would he have offered you a discount On his services if there was a downturn in the market and you lost money?

In the vaguely unlikely case that the cap rate and deal is real and there aren't any significant "gotchas," 25% down should be easily doable.

@Sebastian SoveroThere are 3 main parts to a seller financing deal: down payment, interest rate, and price (4th would be the term).