I have a 7 foot Fatty Knees hard dingy.  Its on chocks with the stern right up next to the mast and the bow is right even with the edge of the main hatch when open.  As far as storing its great but I find it a bit small and unstable.  The 8 foot version would be a lot better but presents problems when storing it on deck.

I use an 8 foot Avon secured inflated upside down athwart ships under the mast and tied down with 4 eye pads while on a passage. A 3 hp outboard for it is mounted on the stern pulpit Edson mount. A folding plywood dinghy floor is stowed below under the V berth mattress with the oars secured alongside the cabin top handrails. Flaking the main requires a little more effort getting around the dinghy otherwise this works well and does not impede forward visibility too much.

While nicely stowable, I found that rollups are just too much of a PITA to assemble/take down on deck and don't take the weight/power of higher HP outboards.  I prefer a bigger outboard than 2-4HP because a) I like to get where I'm going and b) have enough power to bore through waves on a plane.  Also, rollups (esp those with High pressure floors) are too 'flexible' & 'twisty' for my taste (my HP floor Zodiac almost folded back in on itself in a big chop).

While I love the idea of a shippy looking rowing dinghy (i.e. fatty knees, etc.) they are just too tender for me. I like the stability of an inflatable.

I now have a Hypalon Apex 9' lightweight RIB (Apex A9-L). It stows with the transom butted against the mast and the bow falls just short of the Sampson posts. The reason I like the Apex is the tubes are not the larger diameter (ala Caribe) and thus not so wide you can't get around it to the foredeck.  I like it so much that I just priced a new one ($2799 in Central America) since while still serviceable it's getting along in years (10+).  It's powered by a 8hp 2 stroke Yamaha Enduro.

Both dinghy & outboard are pretty easy to get overboard by myself via a 3-1 tackle I hang on a halyard.  And easily/safely towable even in 4-6' seas preventing it from having to be unloaded/unloaded all the time.

Finally if you are, or plan to be in the tropics (as I am) I definitely recommend getting some sunbrella 'chaps' made. IMO a dinghy cover probably extends the life of a inflatable 2X.

Bear in mind my requirements are set by the area I usually cruise in (Belize, Honduras, Mexico), i.e. constant 15-20 kn trade winds with normally 2-4' seas. And that's a calm day. Your mileage may vary.

OK I will throw my hat in the ring with everyone else. I just went through this a couple of month's back. My boat came with a 7'3" hard dinghy that I was determined to make work. It fit nicely between the mast and my Garhauer Traveller and was easy to row. The PO stored it upside down under the staysail boom but I couldn't get around the fact that if there was a fire, I would not be able to escape through the forward hatch. The disadvantage with the hard dinghy was that it was heavy and even worse, unstable in anything over 10 knots. The show stopper was the weight. I couldn't get past having a bad back every time I turned around. So I looked at my available options and ended up buying a 68lb hyperlon Achilles LEX88 for $1500 that is 8'8" long and fits nicely aft of the mast. If I deflate it a little, I can see over it to those evil crab pots through the dodger and I can store my 4 taylor fenders inside it while travelling. I lower it over the side though the lifelines by hand and use my main halyard to raise it up on deck. It is easy to row and stable as all get out. It will fit 3 at a pinch and so far it has been perfect. Good luck on juggling those pros and cons but if it is maximum length you are after, then you should go with the LEX88.