@Aristotle Kumpis  There is no reson you can't combine buying Infill lot with Build to Rent.

A former Rite Aid in Alpharetta, Georgia, has been transformed into Off Leash, a combination dog park and restaurant.

Let's say ARV is $300k, and sale costs are combined 8% so $276k net sale, that puts you at 80% of the total cost, it gives you a ton of margin for errors and mistakes that I would almost promise you will happen in a project like this. 

The combination of lower debt costs and rising cap rates is reinvigorating investor interest, particularly in prime urban locations.

The mountains aren't going anywhere and this is still the busiest National Park in the Country (busier than Grand Canyon, Yellowstone, and Yosemite all 3 combined).

You'll be able to take out half of your vested balance though, so not a ton.If you liquidate it, you're going to have to pay 10% (assuming you're under 50 years old) + taxes owed if it's pre-tax.So maybe a combination of the two using a HELOC on the equity.Is the 401k in the Roth portion by any chance?

I mostly use MLS and local reports, but a tool that combines rental data, bylaws, and prediction models would be super helpful.

I’m unsure if HEL or HELOC or selling the rental, doing 0% balance transfers makes more sense, or a combination.  

@Ryan A Shumaker  All the packages mentioned above are good options if you are doing just a deal or two but if you plan to do multiple deals over the next few years, you may want to look at customizable funds provided by Avestor that combine the best attributes of funds and individual syndication deals. 

@Nayeem Khan there is a local insurance program that combines both a vacant policy with a builders risk policy, avoiding the starting and stopping of multiple policies.