I customized the 8285-B model, because I did not like the crane, which was also in the way for loading the excavator. I also made it RC with 1 receiver and 2 small motors, which can pull it all easily. Did not use more parts, only the RC set and one wheel.
This is pretty cool. I like how you did all the mods without using extra pieces. I also like what you did with the trailer. The orginal trailer with the crane is pretty boring. Check out mine if you have time. http://www.mocpages.com/moc.php/292859