They won't measure. But you might have problems finding a site long enough for your rig at Tek. It is first-come first-serve. A specific site is not reserved for you, and the sites vary widely in size.
There were only three vacant sites from which we could choose the morning we arrived. Two weren't suitable and with the third we had to disconnect to fit. Our fifth wheel is 25' long and with the truck we total 43' in length.
It was a great site but if we couldn't have disconnected, we wouldn't have fit into any of the available sites that day. Some of the larger sites were occupied by tenters and small RVs but you can't make someone move just so you can have a site in which you'll fit.
Savage River has a better selection of sites, and the sites are separated out by size of RV.