I’m not sure what your system looks like but I have a 3 tier with two burners, a cooler for mashing and I make 5 gallon batches all the time.
My hot water tank is a keggel. I typically have about 13 gallons of water to start for 5 gallon batch but I just make sure I have enough, sometimes I boil for longer than 60 minutes.
Depending on what I am making, grain weight wise, I multiply my grain weight by 1.25 to see how much water I need for mashing in the cooler.
I mash 60 minutes and then vorlauf until the mash clears up. Sometimes I add water while doing this because I don’t want to expose my grain bed to oxygen.
As I fill my boil kettle I rinse the grains with near boiling water.
I’ve never had any issues with this method.