I have several homebrew projects with Minicircuits diode DBMs and si5351 VFO/BFO/carrier oscillators.
I first tried si5351 clocks at all output levels via a 3dB 50 ohm pad into an SBL1 with unconvincing results. I seem to recall a scope on the clock pin showed significant loading when attached to the mixer LO port.
I then inserted a 74HC04 squarer and a bigger pad with much better results, but it stops squaring at the higher end of HF.
In my last build, a G6LBQ Bitx, I settled on a single stage 2n2222 common emitter buffer/amp (with broadband bifilar tapped (10T FT37-43) inductor) between the si5351 clock (running at 2mA) and an ADE-1, which gave good results.
Just sharin', YMMV.