Several things come to mind.
One thing to consider is that you are in a WICHE / WUE state. I am not familiar with the engineering programs for WUE (WUE is the undergraduate part of WICHE). However it is possible that your son might be able to get a WUE discount to attend an out of state university.
I agree with @thumper1 that it might make sense to consider the local university, but paying for a dorm room for at least the first year. This gives your son the “go away for university” experience, but at an in-state price. Also, if something goes wrong, help can be nearby. University students do sometimes get sick or have a bad breakup with a significant other, and having loved ones nearby can sometimes very suddenly become a plus. Also, if the student lives in the dorm, it is like a whole new world compared to living at home, even if the student is only 5 miles from home.
We have two immediate family members who got their bachelor’s degree at a university that is just barely not ranked in the top 100 in the US (think 100 to 130 sort of ranking). One many years ago then went on to get two master’s degrees at an Ivy League university. The other is currently getting a DVM at a “top 5 in the US” program. It is possible to do well with a degree from a “top 100” or even “not quite top 100” program, regardless of whether this involves getting a good job after graduation, or going to graduate school, or both (such as working for a year or two or three and then going to graduate school).
Graduating with a bachelor’s degree and no debt can be a big advantage. For example, sometimes first jobs do not pay very well. Sometimes a very interesting and “relevant to long term plans” first job might come available that does not pay well. Having no debt can make it much easier for a recent graduate to be self supporting, and some first jobs might not be practical for a recent graduate who also needs to pay off debt. Having to live with parents to save money while working a first job can restrict what jobs are available, and might not be the typical recent graduate’s dream lifestyle.
And merit aid is possible at many schools. You might not know whether this will happen or not until some time in the last semester of a student’s senior year of high school. I am pretty sure that the various Universities of California are not going to give merit aid for out of state students, but some other schools might. We however did not see any cases where merit aid brought the total cost of attendance down to $25,000 per year, with the exception of in-state schools (and for us schools in Canada, because our daughters have dual citizenship). We did not apply to some schools that are known for very good merit aid.
I would try if it is at all possible to keep the total debt below the expected first year salary. Also, if it is reasonably possible, avoiding a disaster if university takes 5 years might not be a bad plan. One advantage of in-state schools is that if it does go 5 years, the student will still be in-state during the 5th year.
I might also add that when I got my master’s degree at a highly ranked (“top 5” or better) program, many, many of the other students in the same program had earned their bachelor’s degree from their in-state public university. It might be a coincidence but the only case that I was aware of where there were two or more students in the program from the same university, it was NOT a “top 50” program.