I am not joking, but might a flame be a better option than a 'hot' iron? Wafting the flame over the metal heats a larger area and I suggest may get a better melting of the solder and hence better adhesion. More even heating should also reduce the possibility of distortion. Look at some of Tim Watson's builds and use of a flame on his 2mm models.I'd really encourage you to grab the bull by the testicles and have a go at the sides. I plastered the outside of the cage in solder - you will need to put the rear cage in before you do this. Then I plastered the cage in Powerflux. The advatage of using this...it doesn't run away when the model is turned up straight. Then placed the 'skin' on the beast. Made sure that at least 2 holes liked up at the cab end with the holes in the cage. Next turn the heat up on the iron and sweat the 2 pieces together from the inside of the cage. You are going to need a piece(s) of heat resistant material to press and keep the half etch side in place, either that or have pain resistant fingers . The downside of using Powerflux is the greasy residue. Hot water and Viacal to the rescue.
Is Powerflux the same as Powerflow? If so, then I gave it up years ago. I found it really messy and 'demanding' when cleaning up. If it isn't, then . . . ho hum.