Andy is right, especially about the bathroom. The current Troll 540 would give you 2 long benches that make excellent single beds leaving a walkway between them or a monster double. There is also a dinette at the front which makes a single bed. It would seem like a decent choice for a couple with dog and occasional passenger!
We love ours!

we have a troll 540 and just love the 2 single long beds at the back that make into a huge super king?? bed and the single bed eating area at the front.

here are some others points:
the 530 has the option of 2 doubles

a pontos has a bed made up in centre at the back and you can fairy step down each side
http://www.caravane-infos.net/site/actua...riba-pontos-660
the layout depends on whether you want to make bed each time, or lounge
the 555 is slighty wider than the older ones

there is a layout page somewhere

second hand eribas have a few extras already fitted, but each eriba spec was speced to the first buyer

second hand can be sourced abroad perhaps someone can advise further

brand new eriba need extras choosing, this can add up, but really check out the prices from jandi, airstream, and Al

awning wise there are some that are purposely made for eribas or you can adapt a drive away one to fit yourself

towing if loaded correctly is uneventful, but your car will need to be able to cope with either 1200kg or 1300kg which opens up a whole subject in its self
then there is tow ball nose weight limits

it all sounds scary but once you get you head round the various figures, things are not that bad

hope you find your perfect eriba for you