The Icom 421 is shallow in depth and is waterproof, can be flush mounted with the flush kit or by cutting the supplied mount carefully.
Had one and was very impressed, does all you ask for and isn't too expensive. Personally I wouldn't use anything bar Icom now as a VHF having had several others fail very quickly after fitting.
Only problem I had with a 421 was cracking the rear case but this was more due to the clearance between it and the battery inside the console being too small and the battery battered the casing to death
I am now on my second M505 (different boats) and would buy the same again if ever needed.
Ps I am not in the pay of Icom, just happy with their kit and having a bit of reliable electronics on a RIB