I do like the idea because upgrading vehicles can take days, but that, for me anyways, is the “hurry up and get it on the road” kind of guy.
Seems realistically that you would need more bolts or welds to install heavier/stronger frames. I know in real life welding 1/8 steel is quicker than 1/4 steel because more time is needed to get the bead to penetrate deeper not to mention the extra pass needed. The steel i imagine the heavy frames to be in game would actually take 3 total passes to weld properly where normal c channel of the regular cars would work with one pass. Or that is how i am envisioning it when i play.
Just my opinion, but the double time that i see in my version of the game makes sense to me. Although admittedly the 1 hour base time for such a small section seems excessive.