There is a simpler one, as you requested, and you don't need any plans.
Buy a 2X6, cut it 5 feet long, attach the sawhorse brackets for the legs on one side, the vise on the other side. Done!
This horse can be made with inexpensive parts from Harbor Freight. Probably under $20, and under 1 hour of work. Remember to pad the jaws of the vise.
This type of horse is more limited than the one posted above, but it works.