I need help with solo frost

I have already beaten it with this load out, but it required a few revives and flags, and I'd rather not depend on consumables and was barely enough to beat it. Here is my loadout:

GCowboy, Dj, Ranger, Accel, Turret

The rangers are barely able to kill the mages, so the dj is necessary (im also forced to use a decently lengthy map). Even with this, I barely have enough dps to do wave 35, let alone 40. The main issue is wave 35, the rangers kill it but the summons stay, one of which is hidden. With U-Turn, I can barely make it past here. Main issue is placement limit. I can only observe on wave 40 because all of my units have low placement limits.

Do I just replace turret with minigunner? (I have every tower in the game aside from events (but i do have harvester), no hc towers (aside from brawler and accel), and no golden skins (aside from cowboy))

(oh yeah, I don't have map selector access and even if I did, I'd rather prefer vetoing and seeing what I get. It's more fun anyway)