This will make the 5 acres value more than the entire 25 acres.  

How did you add value to the deal?

Boot includes any cash retained or the difference if the replacement property is of lower value than the relinquished property.

When going for a HELOC, aim high on your home’s value — let the appraiser bring it down to what it's actually worth rather than underestimating it yourself.Cash is king.

 - value adds add great value.  

Prioritize stable cash flow, good location, and manageable property condition, while considering strategies like gradual rent increases, expense reduction, and value-add improvements to enhance returns.

It's never a bad time to buy if you can purchase below market value.

It's what you paid, minus the value of the land, plus what you spent on long term repairs (roof, furnace, etc.

.- Value add - How much does it cost to build additional storage units?

I'm unsure if you would be able to combine both loans given that the HELOC is tied to a different property than the one you got traditional financing on.A work around is if you are able to purchase the new property with the HELOC at a significant enough discount, bring the property value up via renovations or additions, then refinance the property, pulling out enough money to repay the HELOC.