PsychedelicSunSet wrote:What are the rules regarding a Vegan/Vegetarian diet in the Sangha?
Don't give directions or even drop hints to laypeople about your dietary preference, but just accept what you're offered and don't eat the meat.
An exception is Wat Pa Baan Taad and its branch monasteries, where even practising vegetarianism this way is prohibited (Ajahn Maha Bua condemned it as "Devadatta dhamma") and any monk discovered to be doing so will be immediately expelled.
Would I be able to retain a Vegan or possibly Vegetarian diet?
It depends how strict you are about it. If you're very strict then it's out of the question because most Thai dishes have at least a dash of fish sauce added to them while being cooked, so in rural Thailand you'd be reduced to living on rice and bananas. But the kind of vegetarianism where you just refrain from eating what is manifestly meat or fish is perfectly doable. For example, there is a vegetarian nun residing in my monastery and although we're supported by very poor mountain folk, on a typical day she'll get rice, forest leaf curry, mushroom curry, boiled bamboo shoots, an egg, noodles, bananas (and sometimes some other fruit according to the season), and sometimes a carton of soy milk.