My boat is one of only 11 full length boats built by Orion. The rest, except one, don't have the unusual engine position as far as I know. But the firm's owner, I am told, built a boat for himself which does have the same engine position. It is not however a Beta and perhaps access is easier.
As Orion are no more, then strictly the answer to your question is "no one now".
A more interesting question might be " why did you buy a boat knowing the potential problems posed by the unusual engine position"?
Alas the answer to that is too long for this time of the evening.
Good idea, thanks Tony.