Here are some actual experiences we've had with trying to get into campsites in N California. We have a 22' overall (tongue to bumper) trailer and a short tow vehicle.
Kirk Creek - Road narrow and boulder on both sides of the site with probably 75-degree angle required us to back the outer front wheel of the TV over a kerb into the bushes.
Gualala - Road narrow and Redwood on the inside corner of the site driveway and cars parked across from it caused us to have to drop the front wheel of the TV off the pavement into the bushes. Site short so had to park TV sideways across driveway.
Bear Creek Reservoir , Sierras - Uphill, direct back-in with a huge pothole on the inside required very creative backing. Dropping into the pothole was not an option. Low branches just cleared the roof.
Fremont Peak - Only way into the site was to make a complete 180 turn. Barely had room. Narrow scary access road before you even get to the CG.
Pismo Beach North - Driveway very short with about 2-3' to spare after unhooking TT.
These are some of the situations we've encountered, so if we ever get a bigger TT I don't want to go above 25' overall. Yes, you can totally avoid these problems by staying at places that can handle longer rigs, but we don't want to be forced away from interesting places. We also have a shorter rear overhang which helps with boondocking off-road. With our compact setup I am confident in choosing just about any CG.