For the archive, I thought I would post what I did.
I ordered a Coleman Mach 8 with the heating strip, no condensation pump, non-ducted. I went with the Coleman for two reasons; first it is only 8" high which is 1" lower than the Dometic penguin II, and second is that people say it is quieter. Since I wasn't tying into my existing Dometic thermostat, it didn't matter to me which unit I used.
I found the instructions to be very well written. Sometimes I find instructions to be written in a way that they can be interpreted two ways -- not the case here. I'm not a super DIY person, but this install was really doable. Getting it on the roof is awkward. I'm sure the neighbors were watching with interest as four of us wrestled it up two ladders while dodging two kids under our feet. I was joking about finding a tall tree to pull the ac into with ropes so that it could be lowered on the RV roof -- I still think that is a good idea.
It is about a 2 hr project.
On my crusader 296bhs, the power was pre-wired (see pic). The duct runs just next to the ceiling opening behind a piece of wood but it does not tie into this unit. If somebody got creative they may be able to remove wood to get to the duct but that is beyond me and probably effects the structural support. The power cable was already wired at the circuit breaker side (yeah!).
Many people say the heat strip doesn't do much. I had the chance to try it out this weekend and it definitely heated the room up -- enough we had to turn it off after 5 minutes (it was probably 55 F outside). We were only on a 30 amp connection so I didn't really use the AC on this unit. In testing after installation, the ac worked well. I see this AC mostly getting used when the Dometic can't cool the RV fast enough when arriving at a campsite in the middle of the summer.
I was concerned the inside ceiling unit would get in my way walking around, but that isn't much of an issue -- I don't hit my head on it (I'm 5'10").
I've got a picture attached of the outside so you can see what it looks like when it is installed.