Newbie with an electrical question

Hello! I just purchased a 73 sovereign and hope to be on the way to fulltiming in about a month. This will be my first time owning an RV. I've done a lot of reading and have gotten some great info from this forum, but I still have tons of questions. For now, I'll start with just one:
The wall oven is missing in the AS that I purchased and so I am replacing it with a large 1500w toaster oven. Does the 30amp power have enough juice to run this if, say, the fridge is running and maybe a tv/pc or a portable heater (the heater is a whole 'nuther issue)? (This may be a stupid question, but I don't understand at all how this electical system works. I read somewhere that I should only use 1200w appliances.) Also, do I need to be concerned about the toaster creating too much heat in that compartment and causing a fire? Thanks for your help.

-Maribeth

[Tinsel Loaf]

When Watts and Volts are known.
Watts divided by Volts = Amps

Example your toster oven draws 1500 watts divided by 120 volts gives you 12.5 amps.
Now add up all your total wattage usage and divide by 120, will your main breaker handle it?

Ok. That helps. So it should all add up to no more than 30, correct?

[Tinsel Loaf]

Sounds like you could exceed the ampacity of your breaker. I try to give my main breaker a 20% reserve by running at 24 amps during high demand.
The reserve allows for inrush current when you want to add a extra something like a blender for a bit. Using less than your rated breaker also keeps it from heating up. It is easier to use less than to have reset and restart everything when the breaker blows.