My 1995 Excella (rear bedroom twins without dinette nook) has a convection microwave next to the fridge on the road side; the 3 burner cooktop is on the curbsie next to the door. For this configuration a gas oven could fit below the cooktop but we would loose the satorage space which is ideal for cooking pots and pans. There is one issue when you convert to a convection microwave; that is it must
be on the 20 amp circuit ( my Sharp shows a FLA of 16 amps and assuming your unit was built with a 30 amp umbilical cord, there is not sufficient ampacity to run both the convection microwave and your air conditioner. This caused a NEC and some state's electrical code oops, and more importantly a CSA violation which was corrected by Airstream sometime mid year in 1995 model year production if I remember correctly and thereafter by adding a transfer switch to the 20 amp circuit so only one of the two units (convection microwave or the A/C unit) could be used to prevent overloading. The switch location varies from model and floorplan. I think a service bulletin may have been issued and may still be available from Airstream customer service in Jackson Center or possibly from your local dealer if he is a good one.
The big issue is the convection microwave ovens draw significantly more power than the low power Sharp ovens used as standard equipment. In fair defense to Airstream, it all depends on how your unit was specified by thje ordering customer or the dealer if it was a stock unit.
Also, I want to credit Lew for I beleive raising this issue some years ago. Maybe one of the forum moderators can find more threaqds for you on this subject.
BTW, I am working in the Eastern Sierra
and away from the home computer and files so I may not be able to answer further Q'suntil I am back in OR at the end of the month should you have more questions.
PS: Sharp units are still made, but the convection unit uses a special face trim adaptor to allow for proper ventilation when cabinet mounted; this is essential!!