We used to have a similar lunch -- ground spam, chunked cheese, pickle relish and a little mayo to bind it. Stuck in whole (not sliced) loaves of bread, sliced in nice this slices but kept the slices together and popped it in the oven to warm. Or, if it was summer and hot, would fix it like a grilled cheese. And, if we were camping, it was put in tinfoil (OK, aluminum foil) and set on the coals of the fire. The new ham or bacon style of spam works pretty good for this, or just fried (no need for oil/butter) to go w/pancakes.