Med, every can of bottom paint will have coverage estimates on the back, based on how you apply it (brush, roller, spray) and how well the material covers. I'd say pick your poison, then see what the coverage numbers are for it.
State and federal regulators have really come down in some areas, requiring boatyards to literally bulldoze away their topsoil and install barrier systems if there are toxins present. So understandably, many yards don't want to let Joe Public do anything that could lead to an EPA action and a shutdown of the yard. Others require you to tarp it and curtain it and remove all debris, and working without retraints is getting rare.