But this won't help with the main issue of simply not sufficient signal strength for the Ka band signals at your location which is by design of course since it is intended for CONUS service.
You're trying to receive the unintended spillover into Mexico which tapers away much faster at Ka band wavelengths than at Ku. So unless you are very close to the US/Mex. border, it's going to be very difficult and hit or miss for the various 99, 103 xpndrs at best.
DirecTV also has an advantage with controlling where the Ka signals go. At Ka frequencies antennas with directional patterns are easier to make (smaller) than at Ku frequencies. Highly directional antennas have a main lobe and then smaller side lobes. The spill over you may see might be from a side lobe where the gain and signal strength are way down; the only way to counter that is to get as large of a dish as you can to gather whatever signal is available. Also, depending on the type of dish you have it may not be entirely reflective at Ka wavelengths. A mesh dish designed for C-band may be partially transparent to Ku band. A mesh dish designed for Ku could be partially transparent to Ka band. A solid metal dish will not have that problem.
Are your dishes prime focus or offset? If your dish fd radio does not match what the LNBF is designed for you are not using the full surface area of the dish.
The slimline LNB is designed as a compromise for the azimuth difference between the aim point for 99, 101, and 103 within the continental US. The azimuth difference between 99 and 103 will be different in Main or Seattle from in southern Texas. HI and AK have different azimuth differences from the continental US. The HI/AK dish LNB may or may not match the azimuth differences for your location.