A sand mound doesnt replace the tank , it is a mound of sand that acts as a filter for the affluent , these are used in areas of poor drainage .

Realeflow on the surface seems like it has a number of features that could be helpful for someone just starting out.

Living in Florida on the gulf coast presents a lot of opportunity, and on the surface it seems like it could have less headaches than long term rentals.

Extensive landscaping, drainage, irrigation, roads, camping platforms and areas, treehouse cabins, and rustic barn rehab.

Many jurisdictions today are asking for structural engineering, site drainage calculations and geotechnical engineering reports on these smaller projects.

Realtors might be another avenue.The details you mentioned are things surveyors deal with regularly and they should know what you'll ultimately need if you tell them your plans.Below is a checklist of things I regularly ask of my surveys:Utility LocationsDepth of SewerMeter LocationsStormwater Drainage & FlowTop of Gutter & Flow Line ElevationsP/L to P/L across the streetStreet RadiusPaper Street dimensionsROW dimensions Sidewalks, curb cuts, aprons along property and neighboring propertiesExisting structures and improvements. 

Most of it is to create better drainage away from the structure to protect foundation and some is for better curb appeal and better use of the back yard. 

half an inch is enough to carry live loads, why do you need more if sub surface is compact?

It's also not harsh on most surfaces.

Since they moved in, we already spent 3-time money on fixing the toilets/shower drain because the drainage issue (found lots of toilets, flushable wipes, hair, feminine products, tree roots etc) at this point, we are happy if she can just move out.