Same weight, different shipping method, how?

We have virtually completed our new shop and come up against what looks to be a show stopper.

How do we handle setting up shipping for two items, both weigh the same but one is shipped by jiffy bag and the other in a parcel?

For example, a beach ball weighing 150g and a candle also weighs 150g. The candle can be sent in a small jiffy bag by standard letter post but the beach ball needs to go parcel post(big difference in cost). An easy solution would be to be able to set the shipping by category (make new "delivery" category with sub categories "letter post", "parcel post".......)but I can't do that.

Price per product seems complicated and kludgy by comparison.

Can I make a feature request for this or something similar to be added?

Jeff.

Edit, for the time being I think we can use volumes to get around this. It is still not what we want as you can also have two items of equal volume that can ship differently in the UK. If we basically plain lie to the software about the sizes, we can segregate our items into the different postal units we need.