First of all, you should never boil your mash before filtering. (1)
Heat water to correct temperature
Add milled grains
Mash for the time needed
Filter and sparge wort
Boil filtered wort
In your case, the best way to filter and sparge would be to use a false bottom, a manifold or a filter screen. If you go BIAB, you need a hoist to lift up your bag and let ...