I do not recommend using an SSD for this purpose. They have a limited number of read write cycles and their higher speed will not be utilized and therefore be of no value.
I do not recommend non self powered drives on the USB ports. Not supported by Dish. May work for a while, but you are overtaxing the power supply. You could plug a non powered drive into a powered USB hub.
Go ahead and get the 3TB drive. It will work, but only use 2TB.
I was just reporting that a couple of items I had sitting around worked for the purpose of an EHD on a Wally. Since I'm using it in a camper that I tend to drag down unpaved forest service roads, the lack of moving parts in the SSD appeals to me, as does the lack of yet another power supply to use with an inverter when off-grid.
Regarding self-powered drives, it's a little interesting that myDish does not specify that the drive must be self-powered. I think this used to be the recommendation but it appears not to be now:
Compatible External Hard Drives
While most major manufacturers' external hard drives are compatible, keep in mind the following guidelines when purchasing an external hard drive:
The external hard drive must meet capacity requirements¹ for your receiver.
The external hard drive must be plugged into one of the USB ports on the back of the receiver.
The external hard drive must have a USB 2.0-compatible cable.
The external hard drive must not use flash memory and should only be a single-hard disk drive.
¹ External hard drive capacity requirements:
Connected to Hopper: minimum 320 GB, maximum 7 TB
Connected to Wally: minimum 500 GB, maximum 4 TB
Connected to other receivers: minimum 50 GB, maximum 2 TB
