Squash vine borers are pita. Pumpkins will root anywhere that the stem touches, so I'll often cover the stem every couple of feet with dirt. This incites secondary roots which is good because they need quite a bit of nutrients to support the large fruit. Doing this also helps with the SVB as they start to kill off a section of plant, the other roots will continue to support it. Also, in hot and humid VA, powdery mildew always strikes me starting in around August, maybe September. The plants go downhill, but by then I've usually got enough ripe pumpkins that I don't really care. I don't bother with any of the PM treatments. I just deal with it and call it a day.

If your soil is sandy, adding some organic matter would add nutrients as well as improve the structure so it can hold onto moisture and any fertilizers you may add later. If it's not too late, pick up some compost and/or manure and mix it into the soil. The more the better. Good luck!