Where sin increased, grace abounded all the more
It sounds to me that at the least you are stuck with at least one section of outdoor switchgear containing either breaker or a BPS with fuses and GFP for either method.
I do not see pricing on this type of equipment so I do not know if the BPS or a breaker is more affordable.
I strongly recommend that you start here:
Charles E. Beck, P.E., Seattle
Comments based on 2014 NEC unless otherwise noted.
I know what I don't know, and I know where to go to find it!