You can do a partial boil, but there are a couple of caveats.
One is when you're making a really hoppy beer, unfortunately. The issue with a partial boil is sort of complex, but the gist of it is that only a certain amount of hops oils can isomerize in water. The papers I've read and heard about say that this limit is approximately 100 IBUs. That's why even the hoppiest beers are about 100 IBUs, even if they calculate out to 200+ (Pliny is a good example).
That's usually fine, since the human tongue is unable to perceive any more than that anyway. But the issue then is when a partial boil is done. Say you end up with 5 gallons of 100 IBU wort for the IPA. Just the act of adding 50% water will dilute those IBUs to 50. There just isn't any way around that. You can get the correct OG by making a more concentrated wort, but you can't get the IBUs higher.
You can make great beer with a partial boil, but I think IPAs would not be one of them due to the limits of hops oils isomerization and this IBU issue.
The one thing that might work, although I've never tried it, is to buy some hops oil extract (I think it's called something like Hopshot). That would not be subject to the same limits, as it would be added to the wort. It might be worth some research if you really want to to 10 gallons of IPA in a small kettle.