OK, some quick answers/ photos.
For the 10-fuse block, I bought this one and am quite pleased, It is good quality construction. If you cannot make the adapter, they have another that has the spades on top.
To connect it, I made some short (~3in) pigtails with male/ female spade connectors. It is pretty tight but I didnt really want to cut all the originals. There may be a more elegant solution.
Honestly, I would not recommend the 6-fuse, 5-relay box. It it fussy regarding the connectors and is pretty cheap construction. I will be looking for a nicer solution but live with this for now.
To support the filter, I printed a U-shaped saddle that press-fits onto the bumper bolt. I may add some glue for security but it fits tight and does a good job of supporting the filter. That said, I haven't put any miles on it yet. I will look for a better photo tonight. If you want the file, let me know.
Lastly, no one asked but I highly recommend this cable wrap. Soooo much better than tape or the cruddy corrugated tube.