You're right, 85 degrees + is a bit warm for a goldfish's liking...but at the same time, it does stress out the fish to be moved every week...it seems as though you're caught between a rock and a hard place.  

I'm not really sure how you conduct your water changes. If you're like me, you may use a large "fish bucket" to syphon the dirty tank water into, dump it out, then refill it with clean water, treat it, then dump it back in the main tank. If this is what you do, maybe you can try chilling the water while it's still in the bucket? Then once it cools down you can dump it back in. Then you won't have to move the fish at all. The big fan is also a good idea, like you said. By the by, I know that floating frozen water bottles can also help bring down the water temperature. Then you may not have to worry about treating the water...just replace them with new ones when they get dethawed.

You have a tricky situation there! It must be hard living in a state where the temperatures get so high.   But, I wouldn't worry too much about your friend....you're just doing the best that you can given the situation. Maybe someone on this forum will chime in who has more experience with this problem than myself.

I think it's much safer for the fish if you'd be cooling the water before putting it into the tank. It really is stressful for the fish having to move every week (or however often you're doing the water changes), they need time to settle in a new place, and get used to the water parameters. I don't think that what you're doing is a terrible fishy sin, but I do think you could try and be more gentle to your fish about it (I on the other hand live in a very cold place, so my problem sometimes is that the tap water comes out being like 17 degrees celsius while it stays on 26 in the main tank... :/)

I don't think it's fishy sin what you're doing, but I like the Brute garbage can idea with wheels.  Let it sit for a day and then it should be room temp, same as your tank.  

Your fish are lucky to have someone who's trying so hard to keep them comfortable, healthy, and happy.  And now you're even on a goldfish forum     If you have to move them, it's better to use your hands rather than a net (if they cooperate) because a net can be hard on their scales and fins, slime coat, etc..

I've used a plastic cup too, with smooth edges.  I pushed the cup below the water line so that a waterfall effect was created in the cup, and the fish would flow into the cup this way, so I didn't have to chase him.