While looking for longer Arca rails to use as a bipod extension I found this interesting offering. It looks to be thick enough to reduce bounce on the bipod and has a bunch of predrilled and threaded holes on it as well as milled slots for using the standard low profile 1/4-20 camera mounting screws for connecting it to a Picatinny to Arca adapter plate that mounts on the gun. This one long plate would allow you to mount your rifle on a ball head, back close to the receiver as well as to use it for a bipod 15+ inches out in front of the receiver when shooting off the bench..
The same seller also has shorter double and single dovetail Arca plates for sale if the 15.7" one is too long. What attracted me to the double dovetail design is that it will be significantly more rigid than the thinner single dovetails. If I end up piecing one together in the future I will post photos. It looks like the 15" version would work well on an RTI Prophet II, reaching to the end of the carbon fiber bottle. A 9" would also work if you don't want the bipod that far out. The Picatinny to Arca adapter shown below fits my Prophet II perfectly and would easily attach to the Pic/Arca adapter with just one new hole drilled in it.
Araca plate Amazon Item Page
Same seller's other items on Amazon that might be useful including the double headed Arca clamping block.
The long Arca plate could be attached to something like this Picatinny to Arca adapter with a camera mounting 1/4-20 low profile screw into the threaded hole on the Picatinny to Arca adapter plus at least one more added to connect the two plates,, going into existing or newly drilled / tapped holes to keep it from rotating.
The double Arca dovetails might be useful if you needed to get some extra height between the picatinny rail on the receiver and the bottom of a large diameter carbon fiber bottle by using a double sided Arca clamping plate setup. as shown below.
The same seller also has shorter double and single dovetail Arca plates for sale if the 15.7" one is too long. What attracted me to the double dovetail design is that it will be significantly more rigid than the thinner single dovetails. If I end up piecing one together in the future I will post photos. It looks like the 15" version would work well on an RTI Prophet II, reaching to the end of the carbon fiber bottle. A 9" would also work if you don't want the bipod that far out. The Picatinny to Arca adapter shown below fits my Prophet II perfectly and would easily attach to the Pic/Arca adapter with just one new hole drilled in it.
Araca plate Amazon Item Page
Same seller's other items on Amazon that might be useful including the double headed Arca clamping block.
The long Arca plate could be attached to something like this Picatinny to Arca adapter with a camera mounting 1/4-20 low profile screw into the threaded hole on the Picatinny to Arca adapter plus at least one more added to connect the two plates,, going into existing or newly drilled / tapped holes to keep it from rotating.
The double Arca dovetails might be useful if you needed to get some extra height between the picatinny rail on the receiver and the bottom of a large diameter carbon fiber bottle by using a double sided Arca clamping plate setup. as shown below.