I would think you could easily get 20a/240v which, depending on your model should let you recover at about 15 miles per every hour of charging. Overnight that's pretty significant. Your only downside is quick turnarounds from long trips, but if you have a supercharger within some range your covered in the unlikely event you need something quick.
I do agree w/ the electrician that your not getting 60a from your panel. But, with all gas, they should be able to calculate a reasonable amount that will be safe and easy.
I'd call the electrician and ask how much they could get, with a target of 20-30a / 240v. You would be pretty happy within that range and it would keep you from spending a pile of money.