Hi Kenagain
Welcome to the site. we have had a Troll 540GT for 16 months and love it.
The best advice that we got was to book a session with Automotive Leisure at Poole and look at all the variations used and new. Sit in them, get the feel of them see how the beds work, work out what size is big enough for you and if you need a bathroom or not. Take your time as it is a big expense and ask AL lots of questions. It was a 6 hour drive for us to get to Poole and we had to book a B & B but it was worth it.
We couldn't make our mind up if we wanted a fixed bed or singles and Cameron at AL showed us the multi-function bed which is available only on the Triton (420 I think) and the Troll 540. This has worked out brilliantly for us as we can leave it like a massive fixed bed if we feel like it.
We also decided that we wanted one with an eating area (and extra bed) at the front of the van and my wife wanted a toilet, so this led us to the 540.
Whatever you choose I'm sure you will enjoy it and have a great time.MikeT