Did a bit of searching and could not find info. on heat loss of their autoformer and Hughes has next to nothing for tech. data on their website. All they say is that at a full 30 amp load it uses 1 amp, but does not say what the input voltage is at 30 amps for a 1 amp loss. Heat loss will vary depending on load and input voltage. Can't even open their box to see what's inside otherwise you'll void the warranty. If using the 50 amp autoformer, the heat loss will be higher but Hughes doesn't give the current loss for it.
With the lack of engineering specs., as an approximation I would use 1 amp x 120 volts = 120 watts as an approximation of heat loss under full load. That's a lot of heat if installed in a small space and I would ensure plenty of ventilation. If the "louvered cover" is the air return grille for the furnace, it may not be adequate in the summer as you'd want crossflow which would mean 2 grilles (inlet and exhaust) for the transformer to get crossflow. A 120V mini-fan might be a good idea along with a thermostat. similar to the photo. Allowing any transformer to run above it's max. temp. rating (unknown for the Hughes) will reduce it's life.
These autoformers (the complete assembly as a unit) are not UL or CSA listed or permitted to be used by the NEC which might be something to think about and look into if installing one inside your RV.
I believe the holes are for condensation drainage only so for an indoor install, I don't think mounting on it's side is an issue.
For your particular mounting location, I would recommend talking to Hughes but I've read that some haven't much luck in doing that.
I used to be against the idea of using an autoformer, but the more I run into low voltage at CGs, the more I think I want one , but used outdoors. Even during cold temps. in early spring and late fall, I'm finding voltage can get low which bothers us now as we are running on electric heat.
