As an undergrad you can do anything you want, but you can't do everything you want.
You can remodel a van, but you can't also go to every home football game and frat party, participate in student government, be active in a local church, work 20 hours a week, and star in several student theater productions. You can do any one of these things, but you can't do all of them.
How well you are prepared matters a lot too. For example, if you have first year college calculus completed in high school and really mastered it, your life is going to go a lot more smoothly than it would if you were trying to learn calculus and calculus based physics at the same time as a freshman.
If you have a learning disability, everything is going to take longer, and you are going to have to spend time reaching out for help more often. If you have ADHD, you are going to be less efficient and more tempted to procrastinate by working on the van when you should be doing problem sets.
If you aren't trying to learn calculus while applying it in other subjects at the same time, and you don't have any personal barriers to doing academic work reasonably efficiently, then you are going to need to spend about 15-16 hours a week in class, and probably something more than 15 hours and less than 32 hours a week on homework, for a combined 30-48 hours a week of academic work. Somewhere in the middle of that range would be pretty typical. If you need more than that many hours taking a regular full-time load of classes in college, and you don't have some sort of learning disability, you either weren't well enough prepared for your program, or you urgently need to get someone who help you learn how to study more efficiently and effectively.
If you are learning calculus for the first time as a freshman in an engineering program, or if you have a learning disability or similar barrier to studying with normal efficiency, you should try to take the lightest possible course load that you can in your freshman year and should limit your non-academic pursuits to the minimum that allows you to be social ties to your peers at college until you are comfortable you can handle more. But you MUST build some social ties or your feelings of isolation will undermine your academics and your ability to get help when you need it.
This said, remodeling a van is a project that can help keep you grounded and sane if you are attracted to engineering because you like working with things on a hands on basis, especially in the first year or two when the curriculum is often more book focused and academic, before you get into the upper division engineering courses that often include at least some more hands on and project based classes. And, if you are a very intense introvert who can get overwhelmed by interacting with large numbers of new people you've never met every day, a project like that can give you respite and mental quiet away from all of them.
Seeing your van mod as a survival necessary way to live, instead of as a fun project, however, is not the best approach. If you are worried about finances: don't! Take out student loans if you must. The cost of a living in a dorm isn't that high, and if you earn an engineering degree you will have the lowest risk of post-graduation unemployment and among the highest starting salaries of any of your peers. Paying off another $20,000-$30,000 of a student loans that financed room and board in college won't be that big of a deal.
Also, don't fall for the common misconception that college is only about taking classes. College is also a time to grow as a person, to meet people some of whom may end up being life long friends, to learn how to be an independent adult, and sometimes even to meet a life partner (something that is much harder once your undergraduate days are over) or short of that to learn from the school of hard knocks what forming a serious relationship with someone is about. You are being socialized into a social class and a profession and developing "soft skills" that cause so many employers to prefer college graduates even in jobs where the specific things you learned in college aren't requirements to do the job. Living on campus for at least two or three years, and living away from home the whole time, dramatically improves what you get out of the college experience as a person.
So, don't skimp.
The lessons you learn from your roommates, dorm mates, cafeteria buddies, and/or frat or sorority siblings are at least a third of what you learn in college. And, they are invariably lessons you didn't know you needed to learn, and thus, wouldn't get any other way because you wouldn't seek them out.