NO! Its a good idea, and I thought the same, tried it, and it did NOT work. Ugh!!!
YMMV, but my fork required a 12mm end cap. I bought that adaptor (it is kinda cool), and it worked great on my axle (I did put a dab of silicon on it so it would not fall out and roll somewhere unobtainable when I changed wheels), but the end cap still didn't fit the fork.
Realistically, larger endcaps may work on some forks, but a lot of people have had the same problem I had - so check first.
It should be easy popping on some DT350 12mm end caps on the front - but I've been wrong before. ;-(
650x2.1 Thunder Burts are a great choice (although they handle a lot different than gravel tires - i think its because they don't have a rounded profile).
I need the front wheel. If anyone just wants a back wheel, let me know!