Today I installed the hardwired 50amp variant of the Progressive Industries Electrical Management System. Now, I am not renowned for my DIY skills but even I could install this (thanks to the advice given on this site). Took me about 45 minutes. The hardest part is manipulating the #6 wire/cable. Taking the front of the electrical panel was more of a surprise than I was expecting. It's a real rats nest of wires behind there.
This unit might be a few more $ than those made overseas but it does so much more and is guaranteed for life. It is also made in the US. The cheapest place I found to buy it was through MakariosRV.com