A gueuze is a beer made from blending “old” lambics, up to three years old, with a “new” lambic that has just finished its main fermentation. The traditional mash program for a lambic is a turbid mash, involving both infusions and decoctions to step the mash through a variety of temperatures. The mash in the all-grain version is a simplified version of this.
Light colors and dry finishes don’t go along with most big beers, but that’s exactly what makes a Belgian tripel great. The road to homebrew heaven is littered with failed tripel attempts, but here’s your path tom salvation — use only light base malts and about 25% clear adjunct (sugar); pitch a big yeast starter and add some yeast nutrients in the boil to supply nitrogen to the yeast.