I've got about $525K in equity in the property, but lenders have told me that I cannot get a HELOC to access that equity for additional purchases because the duplex was financed as an investment - they have said TX law dictates that HELOC can only be used on primary residences.

I just closed one for a client over the hill in Reno, NV. 

No one is ever happy: owners, tenants, vendors.  

my condolences on your recent lost.there are a few ways you can do this, as mentioned above you can take a heloc on your primary residence which will give you a second mortgage, first mortgage payment wont be impacted. you can do cash out refinance which will give you one mortgage and payment. it will pay the old mortgage and give you money in your pocket to pay for the rehab.or you can do a renovation refinance which is similar to cash out refinance but we would contractor involved  as part of the refinancing and they are paid through the loan

I would recommend finding a real estate cpa even for one property.

One of the properties is a three bedroom with no garage that the tenants pay on time but require more of my time than the others .

I guess Cali takes the Trophy on this one Not really. 

We put a sign on every property to: attract tenants, create brand awareness, and to help prevent scammers from using our properties as bait. 

Quote from @Keegan Darby: Hi BP - I’m seeking advice on a property I own. 

Those on other sources of government cash such as disability often may qualify due to overall household income.