Naturally if you're going to install a new cam, you'll need to install the cam manufacturers new lifters and be VERY careful with run-in. You'll also need to pay good attention to the oil you use, becuase there is less anti-wear additives being used these days to save catalytic converters (which hurts solid lifter motors).
With the cam, there is no point in selecting one with a higher lift than you can use at 4000 or 4500, because all it will do is bang up and down for no reason, wondering why you aren't turning 6000 where it provides the advertized power rating. Go for the RV towing package and stay with the low end torque.
Here is a photo of a similar powertrain being installed in a 19' Commander. There may be some similarities. More photos of this installation can be seen here
http://www.network54.com/Forum/424840/message/1185823333/19
I would think the best way to get that transmission out, is to pull it with the motor, and vice versa. Handling it by itself after the motor is out may be more difficult.
You're lucky the 23 has a lot more room than the series of photos I've referenced. Good luck !
Paul