I have tried a few different mashing methods and here is my favourite.
Heat water in a pot, dough in, lid on, put the pot in a warm oven, preheated to approx mash temps. I find the oven temp doesnt have to be perfect. This is far better than an igloo cooler for holding temperature.
After mashing pour the first runnings into the boil pot using a grain bag as a strainer. Batch sparge twice in bowls that you have ready to go by lifting the bag between bowls.
This method requires a bit more dishes but you should have these in the kitchen anyway. The sparging is quick and easy, you will get good efficiency.
You can also do a good mash in a slow cooker on a temp controller, my slow cooker is a bit small for this though.