The people that taught Sir Albert Howard about composting put 1/8 inch of soil on each layer, 6 inches of vegetative waste, 2 inches of animal manure, and 1/8 inch of soil, with the idea, apparently, that the soil would inoculate that mix with the bacteria necessary to digest it. We know today that is not necessary.
Soil on a compost pile will not act as a tarp which would be used to control moisture in the compost pile and would instead tend to hold more moisture than desirable.

Whatever soil you put on top will end up down in the compost. Why would you want to mix soil into your compost?

Sandy soil would be very porous as far as rainfall. If you put a thick enough layer it might keep moisture IN if that's your goal. However it's not easy to remove quickly if you want to change the conditions. It will tend to keep air out also, which is an essential ingredient to good composting.

If you are planning to use the compost where that soil now sits, you could layer it up in place like lasagne. That's about the only use of large quantities of soil in compost.

You already have a gold mine "the soil is black loamy/sandy". Are you planting in that area? If that's not possible, just put that stuff where you do want to garden. Hauling it to compost, then to garden is an extra unnecessary step.

I agree with purpleinopp. Just direct compost it where you want to plant. Wait 2 weeks to give it time to decompose. Spraying with a little sugar water will speed up the process. Saves time and prevents nitrogen loss through evaporation. Some plants will thrive in a high residue environment and some will not. But that is pretty much true of all plants that are appropriate for organic gardening.

Here is a link that might be useful: Garden For Nutrition