Unfortunatelly there is different than sata cable conection to dvd, so without soldering and exchanging cable can't be done ( at least in Jasper model) but after RGH and Dashboard Update 2.0.17349.0 (Released: April 30, 2015) there are over 2 TB limitation can be used, exchanging removeable 2,5" hdd to bigger is an option, also external disk conected to usb with same limitation 2TB can be helpfull.
I believe you can solder in a 2TB hdd to one of the memory card points, but I've never attempted it. @Mateo87 is right on point about the 32GB limitation being lifted for the external hdd. it's now 2TB. however, I believe an rgh can do this regardless. I've always used a 2TB (2 of them in fact) on the 360 'til the first one died for many, many years (using a jtag). I'm not sure about the internal hdd, since I've always used a 1TB drive, but I believe you've always been able to use a 2TB with an rgh. this is also on a phat (falcon and a xenon in the past).
btw, you don't need a dvd drive in the system for an rgh. I know people have used the connection for bigger fans, because I think the dvd drive is 12V instead of 5V with the fan on phat 360s. you will get a blinking power light if no drive is detected. there's a patch for it as well as a way to solder it to where it doesn't do that. I think the system still works normally though, because I know I've turned on my system with the dvd drive detached. however, it's been years, so I might be misremembering.