Check out 81S to I-66 East over to US15 South down to US29 out to US17 at Opel Va. and then down to I-95 at Fredrickburg, Va. That will add about 20 or so miles from the I-77 route, but we have towed that road several times and that would not be my preferred route since you have to be diligent on not just the pulls, but the coasts so you don't overdo things. We live just off I-66 about 20 miles east of Warrenton and we always take I-66 to US15 to US29 and west to the US15/17 split just before Warrenton and the over to Opal, VA where we take US17 South to Fredrickburg to join up with I-95 South. If you have a diesel make sure you fill up at E323 in VA on I-81 just after your cross into Va from WVa at the Flying J.
Larry