Everybody has his own opinions about what looks good and what doesn't. For me, the one you call "goofy" MAN looks better than the Scania/Mallaghan, which is used only for bigger planes, like in reality ( that's a 777/747/A380-class vehicle ).
If you want to alter reality and place the huge vehicle on smaller planes, keeping in mind its platform cannot go lower than a certain height, you can play with the "condition" lines in the SIM.CFG of the vehicle ( the Scania is called CT8000 ), in a SIMILAR way as explained here:
https://www.fsdreamteam.com/forum/index.php/topic,27994.msg183337.html#msg183337However, keep in mind that, every change you do, will be overwritten when updating GSX.