Glyn - you can ask a question and you'll get many different points of
view...
I happen to be one of the anti-roof mount a/c people...
It's not just the looks and weight thing - I fight allergies like crazy -
and while I like a/c - and often need it - I can't handle it blowing right
at me and depending on the size of a trailer - that can be an issue.
I happen to be "high maintenance"...on this issue.
I sure wish I did not have allergies...oh well.
For me - "ducted" a/c is of great interest - not just vent directed from a
common single location. I realize that cool air falls and an upper location
can be most efficient...but in a small space...I'll opt for a little
inefficiency - if I can diffuse the output of air away from me - and if
there is any way of limiting the noise and vibration...so much the better.
If you are using your trailer as an office - this might be of interest to
you.
I realize that the newer models are probably much-much quieter - I've only
experienced the older units. The rooftop unit in my 1980 Avion 34'er
sounded like an commercial air compressor...well sort of. It certainly was
not whisper quiet...
If you are not planning to tow your Caravel - then you have the potential
for being very creative as to installations. You might investigate the
possibility of building a small "service" building for your trailer - neat
and tidy and weathertight etc...??? and it could be the source for your hot
water and a/c (small household heatpump type) that was then piped and ducted
into the trailer??? With a little care it could be done in a way that was
not too invasive to the trailer in case you decide to sell to someone who
wants to travel with it.
This might sound complicated - but you live in an area not known for
severely cold weather - and what with the sometimes higher costs inherent in
RV specialty appliances etc...a base-station service shed might not be all
that expensive - considering the convenience of a domestic sized hot water
heater and lots of nice and quiet ducted heat and a/c.
If you've never spent any time in a small trailer with a rooftop a/c unit
running - you might do a little investigating before you start your upgrade.
Just my own thoughts and brainstorming.
I recently sold my Avion - before I had the chance to upgrade it's a/c
system - so I plan to do a modified system when I find my Airstream. I have
my eye on
the Dometic Corps. Duo-Therm Cool Cat. It's an a/c and heat pump system for
small trailers that can be used by itself - one self contained unit - or a
ducting system can be added. It's a little tricky finding info on it - for
some reason it is not listed on the regular Dometic/Duo-Therm site.
Here is a link to an old article on it -
http://www.rvamerica.com/rvamerica_magazine/dometic_warms.htm
and I've found it listed on this site - which I hope is still current.
http://www.advrv.com/ac.htm
I've not seen the system first hand - but at least at first glance it sounds
potentially interesting.
Good Luck. RL