Have you looked at the Forest River line of R Pods. They have the bunks , the length, height, weight and most other requirements except the heated tanks. We have an R Pod 173 and have traveled all over the country for the last 3 years. We love it!! We've made a lot of modifications to make it better for our use. There is also an R Pod owner's forum that has a lot of info and helpful people. Here is the forest River site
http://www.forestriverinc.com/product-details.aspx?LineID=173&Image=5054&ShowParent=1
Look at the R Pod 172 or 176 model.
Here is the address for the owner's forum
http://www.rpod-owners.com/
good luck
Vann