Then you have to find a backup buyer.The other option is you find the house and have them finance it while you get the rehab done.

For example if I'm doing a gut rehab and I'm taking measurements for a bedroom I would like to know how much insulation, sheetrock, joint compound, trim, baseboard, paint, etc I should buy.  

I plan to focus on multi-family house hacking for at least the first 2-3 years, hopefully leveraging 203k Streamlined loans to let me do minor rehab work on semi - turn key properties. 

NOTE: Youtube is filled with stories of buying a propert valued at 60K at 55K, rehabing for 15K, then a Tooth Farry-esque 110K in equity majically appears.

To build on my question, say I find another investor to fund the rehab costs.  

Do I need a forwarding address? 

Cash out refi for the repairs and rehab and save for rental down payment?

Also do y’all know any good property management companies and rehab/remodel companies?

And always ask for their permission to follow up and see how they're doing -- get their info (as much as possible email, address, etc) and put them in a follow-up campaign and keep contacting them!

As a tip for those who need it, you can probably find this for free in your county's website by seeing which owners have different addresses in their Mailing Address and Situs (Property Address).