Need some advice!
We own a used 1999 Coleman Taos Pop up camper that my little family of 3 ADORES!  Our camper does not have a build in A/C.  Since we live in the deep south, we have only camp during Spring, Fall and Winter so not having an A/C was not a problem.  Now with our little one starting school, most of our future camping trips will have to fall during the summer months AND we recently added a (irresistibly sweet) golden retriever pup to our nature loving family!  Because of these two factors, we are in desperate need of cool air! We first tried a travel A/C unit but it just seem to take up WAY to much room! It is tall and heavy.  It can not be laid on it's side so it doesn't fit in the pop up when it is folded down for travel and therefore takes up way to much needed packing space in our vehicle! Also, once we set up camp, it takes up to much of our already small space inside the camper and because the humidity is so high in the Southeast, we find our selves having to wake up multiple times each night to dump the water tray in this unit.  We are ready for some sort of upgrade!  As a young family, $ is tight but we THINK we have saved up enough at least for a unit.  We are HOPING that we can buy a unit (new, used, or refurbished) and install it ourselves but I am not sure where to start.  Our pop up does not have a pre cut vent or even the 4 tabs/screws in our roof for a unit but there is plenty of room to add one.

What brand do most of you recommend for a small pop up?

Where is the best place to order a unit?

What else do we need with our unit such as installation kits or support/braces?

Have you guys found a good source (website, video, books) to help guide you through the process of self installing?

ALSO..for those of you who have modified/installed other types of air units such as window units, how is it working for you?

ANY answers, opinions, info, suggestions, or tips would be GREATLY appreciated!