In a non-PBGC combo, the maximum deduction on the DC plan is usually 6% of comp. At maximum comp, that means the total contribution to the DC plan will usually be $19,500 (deferrals) + $6,500 (catch-up) + $18,300 (6% of 305,000) = $44,300.
If they are ok with Roth contributions, what you could do is contribute $61,000 - $19,500 - $18,300 = $23,200 as voluntary after-tax contributions and then immediately do an in-plan Roth conversion on that amount. That lets you get your total contributions up to the 415(c) limit.
Of course, voluntary contributions are subject to the ACP test, so this design falls apart if there are any NHCEs in the plan. It also only makes sense if they want to do Roth contributions, which will not appeal to everyone.