Sometimes simple is best.
To mount an object, device, or thing onto a panel, you can simply enter the width of the object and its height off the panel, then enter how wide you want the bracket itself as well as how thick the bracket holder will be, and how big you want mounting flanges and holes, and a bespoke bracket is ready to print!
Print at whatever infill you feel you need, 40% is plenty for me, using ABS, PLA, or whatever is right for you.
Hole = 1 means yes, I want holes
Hole = 0 (that's a zero) means no, I do not want holes.
All other numbers are in millimeters.