I'm thinking about that swing arm oil tank deal and to be honest about it I wouldn't do it. There are two reasons. First is that the unsprung weight of the rear suspension will be increased by the weight of the oil and fittings and that will have a detrimental effect on handling, no ifs, ands, or buts about it. Its also going to get awfully interesting if an oil line or weld breaks and all that oil gets dumped on the rear tire, awfully interesting. The second reason has more to do with the oil itself, it will be greatly agitated and I'd be concerned about air entrainment which would be awfully erosive to bearings. Every hump and bump in the road, ever pebble, will shake that unsprung swingarm like the remote oil tank (hung on the sprung side of the structure) never experienced.
Just something to think about.