Protective gear is a good idea. Hockey gear is the inexspensive route(hockey is big in my area and we even have a shop that just buys and sells used gear), but there is good off road specific stuff for just a little more. I wear an O'Neal/Azonic Flak Jacket under my jersey. It is mesh and has great back protector and built in kidney belt. All the protection is in the right place and it is relatively cool compared to hockey gear. I can't get my old Barbour jacket over it though.
Norman
Norman