Here's what I have observed:
We have a 2005 16' Scamp Molded Fiberglass Travel Trailer with Rear Bed, Side Dinette, Front Shower & Head and have never had any problems with being claustrophobic in it as I have heard. We tow with a 2009 Ford F-150 Reg. Cab Long Bed with A.R.E. Molded Fiberglass Topper with tow package, smaller of the V-8s, extra large gas tank. 2010, on a trip to Yellowstone, we averaged 17 mpg towing. We did very little driving except towing, our daughter & son in law had their SUV so we rode with them when sightseeing. This summer on a short trip, got about 20 mpg without towing in mountains and about 18 mpg towing on somewhat flat with having to climb a pass to get home.
Scamps are somewhat lighter than the Casitas, Scamps have more head room, have R15 insulation with the marine fabric & insulation (some times called 'rat fur' & sheds water & will not mildew easily) which cover the walls & celling, Casita has just carpet. Both keep condensation from forming in them. Casita has an extra foot in the 17' models. Scamp comes in 13' & 16' & a 19' 5th wheel, R15 rated insulation. 13" tires/wheels only. Specs
Casita have 13, 16, 17, no insulation, not as tall inside. Wider beds, more varied layouts for beds. 13 & 16 lower ceilings, small frigs. 14" or 15" tires/wheels. Specs
Scamp & Casita Flooring
and the Canadian Escape
. There is also the all electric Egg Camper
A new make, "Lil' Snoozy"
; seems to all electric as well, but a very nice design, good sized bed. Depending on were you "camp", this would be a really nice trailer if you primary or only stay at campgrounds/RV parks with hookups. This would apply to the EggCamper
as well. I have read reports about them; a very roomy small trailer.
Can't address the differences in quality, not been in but one Casita. But it seems to be pretty good in the Scamp. Main problem with Scamp TT I have found is bed size, just too narrow. The wheel size (13") is another factor. Casita comes with 14" wheel & can 15" can be order as well. All the molded fiberglass TT are well built & last a long, long time & have excellent resell value. Casita have more bed sizes to choose from as well. The Snoozy has a really nice sized bed. Scamps were price less when I bought, than Casita. I assume it is the same now....? Casita is have a lower profile, Scamp more retro look. Somewhat like a plastic Airstream.
We like leaving the rear bed down as a bed, it has a small side dinette just right for the two of us. We have adjusted to the narrow bed by sleeping head to toe. We have really enjoyed the trailer. Easy to tow, to park, to find a site, it is warm or cool and easy to warm it up if cold out & cools off quickly if hot.
Scamp have smaller holding tanks than Casita I believe. We carry extra water in the pickup.
The Snoozy, it seems the man making them is really trying to make a good product. Old Man Snoozy
Many the all electric wouldn't be as bad as I first thought. They are made not too far from Kentucky in St. Matthews, SC. Escape is another one I'd look into as well. But made in BC, Canada. Scamp are made in Minnesota & Casita in Texas.
There is also two Trillium
trailers: The Outback from Canada
and Trillium made in California at one time
. Seems they are to be make in Phoenix soon Trillium RV
(middle of the article) is another new make which may be a good one from what I have been reading. Based in Gibsonville, NC.
For real small units, but fiberglass: Maybe a Little Joe
or Ponderosa (or even a Roughneck): Fiberglass Trailers
would be large enough for your needs, they look neat, but I have not seen one in person. Small but large beds. Not as roomy of course. Made in Henderson, Colorado.