I'm doing something similar crossing the 'Maya Red' with a Choco Bhut and a Red Bhut... but I've been making so many crosses I feel like Dr. Frankenstein without the lab! I don't know what I'm going to do with all of them. You'll need to grow like 20 plants over several generations just for one cross...
You certainly don't need to grow 20 plants, especially f1s (where you only really need 1). Its the f2s on where ideally you want to grow out as many plants as possible to give you more variables and choices, but you don't need 20+ plants each generation to stabalize a cross
You can get a rough idea of how many plants you need to grow based on your goals and the number of recessive traits required to meet those goals...but yes..the more, the better!!!
Imagine you grow out 19, but that plant 20 that never was would have had all the right stuff... tragic :-)
I've made a few crosses and have obtained a few as well... this winter I will have some serious thinking to do about what I will be investing my energy into.
I suppose they'll be on my list for trading at any rate.