IRA to 401k "Reverse" Rollover Worth It?

I have a (to me) substantial amount of money rolled over from 401(k)s into traditional and Roth IRAs at Fidelity. Last year, I wanted to do a backdoor Roth IRA contribution, but couldn't do so without invoking the Roth pro rata rule (AFAIK).

My question is, would it be worthwhile to do a "reverse" rollover from my IRAs at Fidelity into my employer's 401k plan to be able to do backdoor Roth contributions in the future without invoking the pro rata rule? Or should I just put more into my current employer's 401(k) Roth plan going forward?