The ornamental design for a double convexmirror to assist in coupling a trailer to a towvehicle and loading boat on trailer, as shown and described.
FIG. 1 is a side elevational view of a double convex mirror to assist in
coupling a trailer to a tow vehicle and loading boat on trailer showing my
new design, with the broken line showing for illustrative purposes only
and forming no part of the claimed design;
FIG. 2 is an opposite side elevational view thereof;
FIG. 3 is an end elevational view thereof, wherein the opposite end is a
mirror image;