Hi there. As stated, many people have this idea, including me! I did a load of research earlier this year.
The main limiting factor of a series hybrid being that you have both the inneficiency of the ICE plus the losses of the generation process to contend with.
Of course it can and has been done
http://www.evnut.com/rav_longranger.htm
I highly recommend you read the white paper that can be accesed by following the link on that page
http://www.tzev.com/files/rxt-g_acp_white_paper_range_extending_trailers.pdf
I recommend you follow the link on the page yourself though as there is more information available.
The main limiting factor of a series hybrid being that you have both the inneficiency of the ICE plus the losses of the generation process to contend with.
Of course it can and has been done
http://www.evnut.com/rav_longranger.htm
I highly recommend you read the white paper that can be accesed by following the link on that page
http://www.tzev.com/files/rxt-g_acp_white_paper_range_extending_trailers.pdf
I recommend you follow the link on the page yourself though as there is more information available.