I raised the battery compartment by putting shims under the posts holding it, it worked fine and I use 25-27mm lipos, the belt rubs abit but havent had any problems so far. Have maybe 10 batteries in it.
I also think I found out why it was acting so weird, the 15t pulley driving the belt for the front wheels was worn so much that it must have been slipping like crazy. I ordered a new one and hope it will fix my handling issues.