If we could refinance to say 60% LTV, it'd put $370k more in our pockets to buy more properties, and only dip cashflow to $3,600 but effective cash ROI would be 50%-60% with a healthy $1650/mo going towards principal curtailment. 

As stated above make sure you are buying good healthy cash flow properties if you are using a LOC against what you own today.

I drew a little picture so it's not too confusing.In the video, it's obvious that the 4 inch line is in pretty bad shape - lots of grading issues and offsets with major healthy root growth.

I think as Wayne said you can add a new roommate and amend the existing lease with an addendum.I would also screen the new roommate and make the addition of this roommate contingent upon him passing your screening.Also will have to make it clear to your tenant and new roommate that once he is added he inherits "everything".If your current tenant has damaged a wall or soiled the carpet prior to the roommate's occupancy, this roommate is now liable to these damages.

I am not a contractor so I don't even touch a house this old (and very rarely run into one this old in the Dallas area),,,that is the type of house you start to fix one thing, only to discover 3 other problems....I know in some parts of the country houses this old are 'normal',,,,they aren't in Texas,,heck after 100 years and the way the soil moves it probable needs to change it's address

Then I know how much claimable expense I have for the month, as well as how healthy it is doing (cash in pocket) for each month too.I like yours as it looks like it follows the IRS list of expenses for your rental.

First of all, determine the type of termites you have.Are they subterrainean termites that came up from the soil below? 

I posted an ad, say 80' long 10" deep trench of mostly sandy soil and for them to give a quote by email.  

I have a healthy credit line against my home that requires monthly interest only payments which I could simply draw off the line if I wished.

Besides that with basically every home built prior to 1980 will have some foundation issues because of the clay soil here in Texas, it's a given to allocate for problems.