The ornamental design for a mountingpanel, as shown and described.
FIG. 1 is a top-front-left perspective view of a mounting panel showing my new design;
FIG. 2 is a bottom-rear-right perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a left-side elevational view thereof, the right-side elevational view being mirrored thereto; and,
FIG. 6 is a top plan view thereof, the bottom plan view being mirrored thereto.
The oblique line shading used in the drawings indicates that the surfaces of the mounting panel are reflective.
The broken line showing a central perforation in FIGS. 1 through 4 and a surrounding indentation in FIGS. 2 and 4 is included for the purpose of illustrating environmental structure and forms no part of the claimed design.