I've just been through this entire do I/do I not argument with my new boat.
In the end I personally decided not to get an Echomax permanently fitted Ė reasoning behind this being, lack of space on the top of the a-frame and in this position its likely hood of dropping off. I was going to get a bracket fabricated so it could be mounted on the side of the a-frame, but it would have been quite low. Instead I will fit one of those completely useless 2" tubes (mounted vertically, not horizontally where it would be 100% useless) and will carry an inflatable Echomax (which performs better than the Trilens) for reduced vis/emergency situations.
Although I understand and fully appreciate the Solas V requirements, I think that on the whole, for small pleasure craft a mandatory radar reflector is not as useful as for ex. mandatory VHF.