There are several issues..
FIrst: What is the capacity of your hitch? Mine is 5,000 pounds and the RFV has a max tow of 4.000.. My rig is gas. Diesels typicaly have 10,000 pound ratings on the tow hitch, the actual tow capacity may be less.
This assumes a straight hitch, NO DROP no RISE. if you use a Drop/Rise (For the towed car) you must derate because those will torque the cross bar right off the frame (Been there. welded it back).
THe other thing is the added LENGTH of the dual hitch adapter.. NOW this will also affect max tow ratings but ... And this is part guess part science. NOT as much as a drop/rise.
So if your CURRENT hook up is working then the dual hitch adapters come in two types (And have a 3rd)
One has a "Straight through" extension for one receiver and the other receiver is the Drop/or Rise With this type. IF you are not using any drop/rise adapter use the straight through for the Blue Ox. .I do not think you will have a problem but read on.. Put the other receiver above (rise position) for the bicycle carrier.
The other is both a drop and a rise.. IF you are currently using a Drop adapter then.. Well use this type and use the matching adapter
IF You use a RISE adapter you will have to do as I did (Custom made)
NOTE 2:
THey make a bicycle carrier that may slip over the 2" adapter part that goes INTO the receiver eliminating the need for the dual hitch.
Finally. MY hitch.. Was custom made by Blue OX .. They welded it up while I .. Well waited.. I kid you not.
Finally.. IF you use any kind of extension inspect all the welds on the hitch, receiver and cross bar and the brackets where they join the frame OFTEN.
As I said "Been there" when it comes to welding it back together.. Had good welders. Railroad certified aircraft grade welders.. Did a great job.. But it was a long time ago S-S-S (the second two S's are "Son's Service" I think the first name was Simpson) in Indiana, just out of Ohio. .(Heading north west out of Cincinnati right side of freeway)
But with a 4,000 plus towed (What I towed as well Inspect welds and brackets often.. I now tow less than 3,000 pounds
No,, not because of that.. Old car died of old age and new one is lighter.