Assuming 100% of the original HELOC was used to improve your primary residence, that interest is fully deductible.
For the conventional mortgage, the percentage of interest equal to the percentage of the loan used to pay off the mortgage is deductible on the SCH A.
The percentage used to purchase the new 5th wheel "might" be deductible, but not sure.
The percentage used to purchase the truck is just flat out not deductible at all unfortunately.
