A cursory Google search shows that you’re right: in most jurisdictions, unlicensed persons can’t open doors.

We also have our own website with some SEO setup and we get people that find our website through a Google search and reach out direct too.

Meaning, if you google Dorchester, MA (community in Boston) the safety rating it going to look awful because it compares it to a national average.

Also <most times> adding a extra bedroom but not adding sq ft doesn’t help much on ARV specially currently being under 1,500sq ft.

To answer the title of your post, selling fsbo can be a good idea if:- you have experience selling RE- you price the home to sell- you have systems in place to collect inquiries and facilitate showings i.e. call center/email/google forms for screening inquiries, showing agent, lockbox, security alarm, etc. - you have dozens of local agents who can market the property for you and bring you a buyer- you are listing in a desirable area with low-inventory - you are not in a rush to sell

The issue than became adding utilities. 

A capital improvement is not - it gets added to the basis which ultimately reduces the tax due on sale but it’s not tax deductible in the sense in reduces current income. 

My question is if we are marketing this as land, is more value added from the 2020 mobile home or the multiple utility hook ups?

Because we're flippers we can't afford a landscape designer so we go with the style of the home, look at google images based on what kinds of landscaping go with that type of property and then we draw a map of where we want the beds and grasses to go.

And the added cost of the ventilation systems needed to deal with an indoor pool.