I'm curious, would you consider buying 2 smaller deep fryers?
We LOVE ours:
http://tinyurl.com/y5am68

But, yes, fries have to be made in several batches.

But if you had 2 of them going, you could do the first fry in one, and
the second fry in the other at a higher temp, and cruise right along.

This is a really quality fryer, best kitchen gift we ever got.
The element is immersed, so when you dump the food in, the oil comes
back up to temp very quickly, so you don't get grease-soaked food.

And it's really easy to clean.

We don't fry often, but when we do we go hog wild: onion rings to
munch on while we make fries, shrimp, chicken (KFC clone),
beer-battered fish.