I imagine a lot split would also significantly increase cost of utilities as now I would have 3 hookups in that scenario.I am also concerned what would happen to that sweet 3.25% 30 year fixed mortgage I have, which I don't want to create any risk over in the slightest.Any advice on how to frame my counter arguments would be incredibly appreciated.

Some are even offering interest rates as low as 4.75% for a 30 yr fixed loan. 

New signage, added gravel to the park, updated some of the homes, fixed electrical breakers for RV hook up sites, created a website and advertise online.

Are you thinking of more of the fix and flip strategy or buy turnkey and hold?

Learning about fix-and-flips and leveraging private or hard money lenders can help finance flips.

There are plenty of lenders out there that do fix and flip/ rehab lending. 100% on acquisition and 100% on rehab is unlikely, but 80%/100% is totally do-able, and potentially even 90%/100% - all without even looking at your personal income. 

The main issue with rental basement is water if it has water issue usually it is a simple fix .Clean gutters ,discharge gutter  water away 10" away from foundation, make sure you foundation soil is slopped away from it .If you need to buy soil get a clay mix .Cut back any tree too close to the foundation look at the drip line that's how far the limbs are out from the tree .If all that is done still has water buy a sump pump  carry the water to day light away from foundation 10" to 15" .

It's not necessarily something to resolve or fix or perhaps even research, unless a lender won't lend on it because you don't own the surface rights so would not finance permanent structures there. 

Budgeting: Many landlords use the 50 percent rule, which means that 50 percent of your rental income should go to covering fixed and variable expenses, other than the mortgage.4.

You are losing money every month, and you will lose significantly more when they finally move out or you try to sell.The correct answer is to stop trying to fix them.