what plaster to use above vermicrete?

[ga@46]

i have just finished my half barrel oven i have insulated it with ceramic wool and vermicrete on top now i need to make it weather proof by plastering and this is where the problem is. when the oven is working the top and sides are a max.of 35c but the area around the door reaches 75c which is too hot for ordinary plaster now i know the there are heat resistant plasters out there but the ones i have found are for indoor use and not suitable for low temperatures and the rain. is there a suitable weather proof plaster for my brick oven?