Is there a way to incorperate a 17" panel into a box that uses a standard (elongated box) design?

Sure, just build the box bigger.

What about the lens kit? Am I supposed to use the same lens kit as I would for the 15" projector? If so, then I am assuming the LCD has to be a different distance from the lenses compared to the 15" projector setup.

From what I understand, if you buy the standard triplet and then buy your fresnels (bigger ones for the 17") from a different place, everything will work just fine. The distances should be very similar to what the guide states.

Am I right on this?

Sort of. Only problem is the only workable fresnel has a 330 mm focal length forcing you to put it BEHIND the lcd. Therefore you have no keystone correction ability which would really want given the short range to projection this would produce.

There are pro lenses designed for larger lcds but they are currently unavailable.

Sure you can build a normal 17 inch. Its just larger panels require a larger projector so most people prefer to build folded designs to make them smaller. You don't need to and its actually easier just to build a normal projector. No need to worry about all those mirrors.

LL sold a 330mm before moving to the 317mm and people operated the 330 as a split so there isn't a requirement to put it behind. The 317mm is better but the 330mm stil works split or unsplit. The only reason to use behind was the too long focal distance with the old PRO fresnels.

will the standard pj measurements need to be changed for fresnel lens and triplet placement when upgrading to a 17 inch model? Or do you literally mean just make the box larger to accomodate the 17 inch lcd frame?