>>What if I set the receiver so that there is no sub and put the front channels as large, shouldn't that redirect the bass to the front speakers which could then be extracted by the sub?

You would expect this, but not all receivers work this way. Yamahas definitely do, HKs seem not to, and I think the rest are split about 50/50.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8