MY suggestion is the Green Mtns in VT. Lots of opportunities for dayhikes up that way. There are plenty of offroad trails in Maine-old logging roads, etc-reach out to some of the offroad clubs in the new england area (google some-I contact bay state jeepers all the time, they have good info on trails in NE). Snow will still be an issue in April, as will mud. Be prepared for it, especially farther north.