Cooked pineapple with jalapeños actually goes well together, but you're right about it going downhill fast when the pineapple gets even slightly less hot.
Santitas or Julio are definitely a necessity. Everything else is too thin or too salty or spiced and fucks up the flavor.
You need a soft cheese. Cheddar can still be a topper, but you need a cheese that stays relatively liquid at a lower temp. I'll heat up half a brick of Velveeta with a couple cans of this and blend them together.
Chips and cheese are your base.
Meat: ground beef, shredded pork are my preference
Cooked (baked) toppings: sliced black olives, sliced jalapeños, chopped onions red or white, chopped bell peppers
Fresh (not cooked) toppings: lettuce, black olives, jalapeños, tomatoes, cilantro
Additional toppings: sour cream, guacamole - a good guac can make even shit nachos awesome, shredded Mexican cheese or cheddar or white cheese, squeezed lime