I have two rentals at the moment, and I am trying to scale my portfolio at a rapid rate. 2 starter questions-Q: How do I analyze the deal with knowing I will have a Heloc payment and a mortgage payment.

By "lowly sponsor" I'm envisioning someone with a couple hundred grand and experience who quits his/her job to raise $xmm and acquire a large 150+ multifamily property or something of similar scale in an alternative property type. 

For years I've used spreadsheets where I input each booking every month giving me final numbers I can trust, but as we scale and add more properties I'd like to find a more streamlined solution.  

Partnering up is not a bad way to scale.

I have a similar mindset of getting my hands wet and learning before scaling into syndications! 

One scale  and moving up in asset class whence you startedand appreciation.. either organic or forced.

I have roughly $80k-$100K in equity and would like to scale into another market but because CO is such an appreciation state I'd rather not sell a potential equity building machine before really allowing the equity build up to happen.4) Lastly, I am thinking of changing my mortgage into a Heloc and being able to utilize the equity that way.

I would also check out getaway.house they have tiny cabins out here in the Northeast and although it seems to be a somewhat larger operation, this is exactly in the line of what I was thinking, but on a smaller scale as it would have been just one little cabin,  when I wanted to embark on my original idea....but they are on to something....but like I said financing for this type of thing is hard cuz you can’t get traditional financing for it....so maybe a small group of investors with some cash could work... 

Same way, say, the very large banks manage X number of bank branches-- that is, they do it poorly but have so much scale it makes little difference to their bottom line.

If you can build trust and show a track record you should be able to scale.