We've just done exactly what Loopy suggests.
DD still has growing room in her sleeper, but she's raising her head now, trying to sit up and it's dislodging the restraints from her shoulders. We've just bought a BeSafe Izi Combi which will last until she's at least 4 (going on weights). She's 7 months now, not 10kg yet.
We bought the Sleeper as we had booked a (driving) holiday in France before we found out I was pregnant, and we didn't fancy stopping for an hour every two hours, on a 12 hour drive, if we didn't absolutely have to.
We love it, as does DD. It is also suitable for overnight sleeping, so you don't have to take a travel cot with you. And it fits on the Britax pushchair wheels, so you don't have to buy the carrycot attachment for that either.
Also, the baby won't know anything different, so the view is a moot point. However, DD has a perfect view straight out of the window, doesn't have to turn her head - the world is quite literally at her feet 
If you weren't so far away, I'd offer to show you.
Sorry for longness of the post 