Just to make sure things are clear:

Crank sets / Chaingings for road bikes
Compact double = 50/34 or similar (can be 50/35, for example)
Regular double = 52/39 or similar (can be 53/40 but I can't imagine the uses for that!)
Regular road triple = something like 50/40/30

For mountain bikes and hybrids all the numbers would be lower.

Touring bikes usually have a triple, and sometimes even a "mountain-style" triple if it's for loaded touring on long distance. (Not applicable to you probably.)


Further information:
Weight of a pair of pretty average panniers, empty: 1.6 kg or about 3 pounds
Weight of a fairly light rack, NOT heavy-duty: 500 g or about 1 pound



Yes, please keep us posted about what you end up doing!