I know there are plenty of comments both ways on the connection of the PV negative wire from the panel(s) to a RV frame, then connecting BOTH the negative terminals of the MPPT to the frame as well (albeit a different spot on the frame). I completely understand that the PREFERRED way is running a separate wire for the PV connection, that’s my preferred way as well… BUT, If that is highly impractical, and using a SmartSolar 100/30 MPPT (where the negatives are connected internally in the unit), can you connect the MPPT to the frame as well. There is of course a PV+ single cable from the panels to the MPPT, just not a PV- Cable (That’s connected to the frame about 20’ away and hidden).
Looking for info before I make the move
See the diagram attached to see the negative connections. The “Ground” symbols are wired connections to the RV frame as to complete the negative circut, and NOT a rod in the earth. Thank you all for your constructive responses!! 
