Russ,

thank you.

the main problem in setting a production line is engine availability.
For LCVPs there is no problem but MTBs are relatively complex pieces of engineering.

The MN ASW force is already quite developed. In addition to the 8 DE procured (and Benson-class are actually mix Fleet/escort DDs) we have 6 RN Hunt and a lot of Flower and River escorts (Canadian built).
We have 32 PCs and 52 SCs.
this is already quite large a coastal force (and we still have French built ASW Sloops and US built PCE).

It is not possible to get more ships manned. This is the main issue.
Never forget that procuring US ships and crafts is just one side of the coin.

the main difference with OTL is that we still have a lot of the "initial" French Navy (no scuttling in Toulon). Even if losses have been high, there is still a lot of ships and they are consuming a lot of manpower.

Jacques