A couple structural facts..
For laymen's term explanation ,here it goes. The MAJORITY of fasteners in an RV (or any plane) are loaded in "shear". The strength of the joint is the ability to carry load into the members through the fasteners. In a shear loaded installation, the surface area of the inside of the hole that contacts the fastener is the key factor in how good the load can be carried. A rivet, is a "hole filling" fastener. When installed by driving it, the shank expands to fill the hole nearly 100% if its even remotely a good hole. Therefore, you have good shear load transfer. A bolt however, must have a better hole/bolt shank mate-up, typically only achievable by reaming to a true and round condition at nearly the same diameter as the bolt is. This gives you best load transfer. That is the reason Vans does the spar carry through with a closer tolerance fastener and hole. Ultimate failure of a shear joint occurs when the fastener has movement within the hole and eventually leads to a crack. I could go into much more detail, but the laymen's explanation is really all that's needed. I have drilled millions of holes in my 42 year career, but almost never used a reamer in skin (except if thick skin and a fastener different than a rivet)..its really just a waste of time and money.