Over the years, I have learned places to access trails along my routes. You can find access point from 
face book groups like Truckin' Runners and Trucker Trails. Check out the www.rideandroll.me website as well. Look at the satellite maps. Sometimes you will find a trail near your customers. I know that I have. Pay attention. Look for trails as you drive and not truck parking near them.
Most of my runs are upper mid west. We run a lot of Green Bay to Saint Louis to Columbus triangles. I will hit a few of my spots. Here. Coming down the newly christened interstate 41, get off at exit 97. There you will find newly built Loves and Kwik trip travel plazas. Either one will give you easy access to the Wild Goose State Trail. My next trail stop on the way to Saint Louis is exit 160 Market Street off of I55 in Bloomington, Il. The Constitution Trail is just a few hundred yards behind the Pilot. The 
Saint Louis metro area offers many trails and bike lanes. Look for trails near your customers.
I have a few trails that I can hit along I 70 on the trip from St. Louis to Columbus. The first one is in Effingham, IL. It is closest to the Petro, but can also be accessed from the Flying J, or the TA truck stops. There is a bridge that crosses over the interstate. There is a trail about a mile from Loves in Richmond, IN. The access is a bit of a challenge. The Wolf Creek Trail near Brookville, OH (I70 exit 21) offers much easier truck access. You can park at Arby's, McDonald's, or Wendy's to access the trail.
Their are 2 good trail access point off of I80/94 near Gary, IN. If you park at the Petro or the Loves off of Exit 9, there is a trail that runs along the north side of the truck stops. If you park at the Cabela's off 
of exit 2 there is a trail there as well. One of my favorite trails is the Des Plaines River trail in Illinois. I accesss it in Wadsworth, IL. There is a Dunkin' Donuts with truck parking at the Southeast corner of US 41 and IL 173. The trail runs about 100 yards from there. If you prefer the toll way you can park at the TA trucks stop at Russell Road. Head east on Russell Road about a mile. There is a forest preserve there with many trails including the Des Plaines River Trail.
After I clear Milwaukee the first truck stop is the How Dea truck stop at I 43 exit 107. You can take the sidewalk west for about a mile to the interurban trail. There is a small truck stop and a McDonald's just off of exit 171 Denmark. From the truck parking go east on the sidewalk for about a mile and you will find the Devil's River State Trail.