Also if anybody has any suggestions on books to read on the subject of HELOC financing or any similar methods I would greatly appreciate those recommendations as well!

The seller data is useful but it must be evaluated within the context of your own investing knowledge and experience.A local property manager who manages similar assets can also provide useful data.Use your local market knowledge and experience to develop a proforma you feel confident in and proceed from there.Arn

I had a similar situation and simply rewrote new and separate leases and deposits for each tenant.

Not exactly the same, but I have found it to be similar enough for my liking.

But I hit a wall.First: Trying to find out what similar properties in the area (10 m radius) rent for, I used rentcast and rentometer for this, but they gave me two very different results.

You might use Zillow's zestimate, a CMA (Comparable Market Analysis) provided by a realtor, or just your own analysis of recently sold similar properties.

I received similar mail from them.

I'll just add, that if you've done these types of deals or similar deals before, having accurate and up-to-date financials (aka bookkeeping records) for those previous deals to be able to analyze the numbers would be a great tool to use to make informed decisions about future deals.And, even if you haven't done deals like this before, keeping updated financials for the deal you're doing is going to be huge as you're making decisions throughout the rehab.We call these data-driven decisions.

I will check Zillow and rent cast to see if the projected rents are similar or different to what bigger pockets pulls from.Good point about adjusting variables on the calculator.  

Renting allowed them to cover costs and build equity, while selling in a hot market helped them capitalize on the home’s increased value.Let me know if you’re interested in financing options for similar deals, happy to assist!