Installing a Maxxair Fan in a Ford Transit 

Because we mostly bought the van for our dog, Bixby, the most important install was our Maxxair Fan. (Affiliate link: amzn.to/3CfJ4iS)
The project was more scary than it was difficult, and we were able to do it successfully in about 7 hours, including drying/curing time. It's been on our van for about a month, and it's been working well with no leaks.
For a real how-to, we used ‪@MoserMakes‬ tutorial. It was great!