Probably would work.  Depends on the size of the inflatable bed.  We have one but only occasionally use the extra room.  We are happy with it's durability and ease of putting up, although we had to figure that one out.  It mounts and dismounts from the Westy easily, although when raining the attaching fabric has to be taut or supported with a pole to keep rain going the correct direction.
When we had children, we put them in the lower bunk until old enough to sleep up top.  That worked out very well.
Dave B.-----Original Message-----
From: Ryan Perry <rjdperry@GMAIL.COM>
To: vanagon <vanagon@GERRY.VANAGON.COM>
Sent: Thu, Feb 6, 2020 11:01 am
Subject: Add a Room

What's up Vanagon List...
My wife and I have a 1yr old and finding that room is needed to continue
camping comfortably.
We are looking at the Add-a-Room from BusDepot. Seems like a good fit for
us. We like it connected to the van, the flexibility with pull up awnings
and bathtub floor.

https://www.busdepot.com/details/addaroom/

However, we were curious if anyone had any info or better pictures than
what is on the site of the interior? We are trying to see if perhaps
putting an inflatable bed in the Additional room area is possible? We have
a few festivals coming up and need to get something sooner than later. At
this price point I would rather be certain what I am getting before pulling
the trigger.

thanks ya'll!
Ryan Perry