how much water to use?

I've got two brews done and deliciously gone now. This is absolutely the best hobby ever. I saw in the recipes section Yoopers clone of dead guy ale, and I decided to give it a go given that it's one of my favorite beers. I've got all the ingredients here for the extract version, and I'm now wondering how much water I should use. My first two beers were brewers best belgian tripel and brewers best robust porter. I used 2.5 gallons and added another 3 gallons or so after transferring the wort to my fermenter to get it up to 5 total. I'm concerned that I'm going to wind up with something too thick to transfer effectively if I use 2.5 gallons. I've got a 5 gallon brewpot, but I'm brewing on my stovetop which takes a very long time to boil just 2.5 gallons. Should I up it to 3 or even more or just use 2.5?

I would brew as much as you can handle. You will get better hop utililzation with a larger boil.

If it's a 5 gallon recipe, boil the largest volume you can, then just top up to 5 gallons in the fermentor.

Hmm, so more is better here. Good to know. Thank you

I'll give it a go with 3 or 3.5 gallons instead. It'll take ages to boil a full 5 gallons on my stove.