W/out a doubt weldments would be alot faster. Imagine using sketched lines to define the size and shape of your complete model. Then going through the model and selecting various lines and applying a material [tubing] to each line. The miters and copes take care of themselves. Very quickly you can create a weldment frame of pretty much anything.
It is certainly something to look into learning, however it is concidered a more 'advanced' modeling method. [Not were a person should start learning Solidworks]
As to your current question. I typically use planes and points for something like this. Makes sure there are planes through the length of the part [down the axle length and perpendicular to the length etc] as well as points on the ends of the pipe and using these you can make most of the needed mates. It does depend to some degree on how complex your model it [ie if your designing a car frame or a bike frame [hard] or a broom rack [possibly easier]]
Fwiw
JFG
JerryFlyGuy
The more I know... the more I realize I don't
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)