I run Savox in my FE tunnels. With the G30 I can run the boats back in upside down. The servos are fully submerged. Never had an issue and never do any maintenance.
You could try adding stumble blocks. Not sure how effective they would be on the older design but they can be double sided taped on. If it doesn't help, then just pull them off. Majority of the newer hulls all utilize them.
His props are great. I have a bunch of them. He doesn't always communicate really well. Some have taken two weeks to arrive and some have taken two months. They are well worth it. Just know upfront that you may have to wait a little while.