My plan is to live here, make some improvements, for the next two years or so until I finish my dissertation and graduate from PhD, then sell the place as I move to somewhere else after graduation. 

If you have a plan on where to invest it to get a better return then go for it.If not then look at ways to improve cash flow such as sub metering the electric, water and gas and arguing your property taxes down with the assessor's office (the tax assessment dispute typically takes place once or twice a year depending on the city). 

I remodeled the unfinished areas of the house and improved the landscape.

Our lease does say, 'jointly and severally liable'...Would it be better for tenant #1 to sublet the 2nd bedroom and be responsible for collecting his half of the rent from the new tenant ?

If:-Current joint primary Mortage with spouse 300 k-Won’t qualify for conventional or investment loan because dti is too low (they ding you for entire primary mortgage plus taxes)- liquid assets 600+-current home equity 800k+Looking to buy second home for short term rentals / investment around 300-450kBesides HELOC what are best loan options and why?

In general, many residents are OK with lot rent being raised as long as the costs are justified and they can physically see where the money is going with the types of upgrades and improvements made to the park.

Questions:I am wondering how we should officially consider and designate “ownership” of the property and on the title report.Should We consider it joint tenancy?

My father also uses it for his home improvement company for years.

With that said, beyond people stumbling upon your VRBO/Airbnb listing, driving traffic to your page is tough and something I will be working to improve. 

Held jointly in an escrow account, the amount ranges from 1,000 to 3% of the purchase price of the property.