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.

Purchase price: $62,000 Cash invested: $60,000 Project in progress: Off market dealPurchase: $62,000Rehab: $60,000ARV: $165,000 What made you interested in investing in this type of deal?

They will lend you their IRA money.My friends and family lend me 100% of the purchase price AND rehab money.

Typically starting with a smaller rehab budget of $50K or less (maybe a max of $75K) and avoiding a 1 to 1(or higher) ratio of purchase to rehab costs is recommend when you are first starting out. 

To defer all tax you must purchase in total at least as much as your net sale.

I have a followup question - I will realize a lot of capital gain from this home in Idaho, so I think unless I purchase a new primary residence I will have to pay that capital gains tax. 

Is this LTV based on ARV or the purchase price? 

Purchase price: $80,000 Cash invested: $145,000 Turning a 3/2 into a 4/2 duplex for short term rentals.

You are definitely going to want to get a lawyer and as soon as possible.This will sound harsh.In your story, you have made a number of very poor decisions about how you purchased and managed this property. 

Plan is to purchase a couple homes over the next year.