Hey Stef,
Glad you got good service from your direct PV to heating element setup. Bravo!
I see there are some Chinesium MPPT charge controllers that will do up to 100A at 12V, with 200 max open PV string, which is a good match for your setup. I would not go less than 200V max rated so you some headroom for spikes and such. Your 4 panels in series open circuit voltage will likely be as high as 4 x 44V or 176V.
So the two figures to look for are the rated current for 12V nominal battery, and the max PV voltage.
Most of the ones that match your needs seem to be out of stock.
Chinesium is a bargain price but the likelyhood of failure is significantly higher. This is a concern for this type of controller as when it fails, cheap or expensive, it is likely that it will then apply the full PV voltage to your battery. This has caused the destruction of very expensive lithium battery banks, as the over voltage safety protection can't handle that high of a voltage so fail closed also. This cascade of failures then destroys the entire battery bank. There has been much discussion of this issue and there are lots of ways to add some safety hardware. One way is to use a cheap 20A or better rated solid state 230VAC relay to short the PV panels if the regulated output goes above your equalization voltage. A 12V, 1/8 or better Watt zener diode to the SSR control will do that. Once its triggered, the relay will not turn off unless you open the PV breaker.
I'm not up on the high end charge controllers. Midnight solar does have a model that is rated for 200V PV. $650 US
https://www.thesolarbiz.com/midnite-solar-classic-200-charge-controller.html?gclid=CjwKCAjwp9qZBhBkEiwAsYFsb557Er92paX7G92NCg8ApiMg-kZTMpCHzpbCiCwv6jPxHiBZNSQdhxoCAa4QAvD_BwEMakes me think more fondly of the Chinesium units with an added safety SSR and zener.