Yes, you can drive up on blocks if you want. Or you can put the front wheels into a depression in the ground (if you can find).
But I've always used the jack to engage the WDH. 7 seasons with our popup camper (400 Single Bar WDH), and now 6 years with the Surveyor (Equal-I-zer). This year, my hand-cracker felt a bit stiff, no doubt because I've never lubed it. Felt like something might break. So it was a good excuse to install a 4500 lbs Husky Brute power jack that I found on Amazon. Love it!!
thebrakeman ('70), DW ('71), DD ('99), DD ('01), DD ('05)
2004 Surveyor SV261T (UltraLite Bunkhouse Hybrid)
2006 Mercury Mountaineer V8 AWD Premier
Equal-i-zer WDH (10k), Prodigy Brake Controller