My goal is to be filthy rich and set my family up for generations. maybe I should pay the mortgages faster?

Over the years, the lot rents for parks nationwide has increased at a faster rate.

If you are a hard-worker, feel free to send me a PM, I might have know someone looking for a faster learner I can introduce you to. 

I'm looking more how can I grow my rental portfolio faster. 

Rents will rise much at a much faster rate, so the challenge of finding cash flow (enabling more investors to become "capable") will gradually recede as SFR cap rates gradually expand - it will be a process, not an event - over the next few years.

But, the higher income you have right now, the faster you can work your plan. 

It may sound nice to pay a 6% management fee but the extra fees can add up to be more than the other company that charges 10% with no additional fees.

Keep in mind many get investigated not all get charged or anything happens..

.: I would go HELOC for sure that would be best as others were saying the lower cost for the money changes between paying a higher rate for a personal line and typically personal lines they want a higher monthly charge as well independent from the interest rate.  

Additionally, working in a small-town market taught us how to effectively price properties for faster sales without compromising profit.