Welcome to the gang Gus, enjoy here and out in the playground.
I'm not sure if you are asking for dimensions of the "2003 and new coaster" or just after a few ideas for a floor plan, i.e. where to put beds, fridge, shower, sink etc etc.
If dimensions, maybe contact Toyota if you haven't already or maybe ask Mr Google.
If ideas, maybe have a peak at the for sale sections of forums, web sites etc for internal pics, might give you some ideas.
Most people have the bed going across the back and maybe a bunk down one side for kids, as you say "family".
Just a couple of thoughts.
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Live Life On Your Terms
DOUGChief One Feather (Losing feathers with age)
TUG.......2014 Holden LT Colorado Twin Cab Ute with Canopy
DEN....... 2014 "Chief" Arrow CV (with some changes)
I am sure that the members who had/have a Coaster Bus motorhome will come along to help you out
I was looking very hard at second hand Coasters, prior to buying what I have now Apart from what Dougwe has already described, with bed layout, and searching the Internet, I can add no more, except to say:-
I did not actually see what I would describe as a standard floor plan for a Coaster Bus motorhome, as they were all slightly different, with their interior design, and fittings
Whilst I've never converted a Coaster, I have converted several Buses and Coaches many many moons ago. With any conversion there's no such thing as a standard layout. Your conversion should be custom to include all the things needed to fit your purpose. Best advice I can give you is grab a pen & pad and first list all the things you want included and then start making some scetches of layouts to include all those things needed.
When you have a couple of layouts in mind, then transform your ideas onto some graph paper and rework your layout/s into a scale drawing to see if it will work. When it works on paper then start your build but be prepared to make changes as you go. A general rule is that the fitout should weight less than all the seats removed from the bus.
Hope this helps, Steve.
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Steve, Di & Ziggy We named our Motorhome "Roadworx" because on the road works "On The Road Again" Ford Transit with 302 Windsor V8 conversion, C4 Auto, 9 Inch Ford Diff All Lighting L.E.D., 260 Amp/h AGM, 530 Watt Solar + Kipor Backup Gen.