When I had the bottom off my 1150 I noticed there is a large space in front of the basement drawer and behind the fresh tank that is just dead space. It is there because it represents the room gained by it's longer length compared to the 990 which used the same tanks. I bet you could add more grey capacity to the new 1140/1150 like you could on the 2010.
I always wondered what they were thinking too by making the black bigger than the grey. It was always annoying to have grey water backing up in the shower and still have unused fresh water. Ridiculous really, I hope the engineers figure it out someday or are they just catering only to resort campers now that run full hook-ups everyday?
I know my 2010 1150 grey tank didn't overflow in to the black tank even though I'd have to be really sick to fill a 43 gal black tank so they might as well have an overflow.
montecarlo31, showering outside in the summer would be fine if you don't have neighbors but in the winter I unhook my outside shower lines so they won't freeze. Icicles dangling off my nethers doesn't sound too appealing so showering inside would be a must.
Buzzcut1, when I lived in mine I could go 14 days on the 61 gal fresh I had. It sure was nice not to have to leave and find water any more often than that. Camping I could do with less like you. I have only 25 now but have plans to add more as that isn't enough.
In my perfect camper the fresh would be as large as possible and the grey would be nearly as large within a few gallons because some is going into the black tank. I think about 20 gal black would be sufficient for any length of camping I'd do.