Sounds a lot like
https://muscatinecountyconservation.com/mccb-areas/deep-lakes-park/I'm all for lending a hand depending on the travel time...shoot me some info. How well does the pit ice over? Icing bass can be very effective, so long as the fins don't freeze you have a ton of time to measure, scale, tag/mark, etc. They're extremely aggressive and easy to catch in the winter.
What are the rw's of the bg and bcp like? I've fished a similar pit where all the predators were skinny (but long), bg/bcp were big and fat. It never froze, held vegetation all year in the clear water, lots of hiding spots for young bg/bcp to grow, feed, and not be eaten. That pit had not been fished in years and nature had ran its course - once folks started culling bass and some of the larger pan fish the LMB rw's are way up.
BTW the combination of goose crap and dead vegetation in clear water makes an excellent sticky much bottom for perch, bg, walleye, etc to feed on in the winter time. You wouldn't think a sand/gravel pit would have these bottom types but they're pretty common
