Late boil

I have a 24 gallon kettle that I can get 16.5 gallons finished volume easily, I want to try to squeeze another 5.5 gallons in there, for a total finished volume of 22 gallons, but I would have to add most of the last sparge later, after the initial volume boils down, my question is has anyone done this, and do you forsee any problems? Will I have any hot break issues for the last sparge water addition, since it will be very low gravity I assume it will be minimal if any? And what will it do for the IBU's, I assume not any change? I will look forward to any help on this matter, thanks in advance.

No, Problems I do it all the time. I't thin any way, you may get a more dextronus wort which may lead to a little more body in the beer. But it works great.

I made the mistake of doing that 2 weeks in a row while my larger kettle was ordered. Both of those beers were dumped after weeks of letting it age to see if the DMS would fade. Still tasted like canned corn a month later so I got rid of them. I will never make that mistake again. Any mash or sparge runnings are brought to a very strong boil for no less than 90 minutes from now on.

You could opt for a small pot/kitchen stove boil for the end runnings. I recently read a DFH 120 minute IPA thread on here where the person had a small pot boiling in the kitchen because his outside brewpot was overfilled. He had his wife doing hop additions inside and when there was enough room outside, they brought it out and combined.