ivano,
Thank you for the pictures. Nice modification! I understand you are saying that it will fit diagonally without cutting but it may not be the best. I now see that you recommend cutting it.
Do you think the Ambient SRS100LX might be better than the Davis 7714 so that it does not need to be cut? The Ambient SRS100LX is larger than the Davis 7714.
I believe you can also order a sturdier metal bracket from Ambient for about $15.00 or so.
The "Powder Coated Aluminum" L-shaped bracket costs an additional $17.00 currently when ordered as an option to the SRS100LX and $25.00 when ordered separately (i.e. as SRS100-METAL-BRACKET),