On a Gen I, the oil filter is mounted at an angle...and, at least on our 2, impossible to get off directly without sliding it rearward quite a way, then pulling it out from between the frame and the engine.
Interestingly, I changed the oil on our red/yellow 96 RT/10 JUST BEFORE the 998 recall was done and had a problem very similar to yours...while on my 4 post lift. So, I slid the jack bridge under it and used a small bottle jack to lift right corner, allowing the right front tire to droop, and slid filter out over the front suspension.
At first, I wondered about a problem with the right motor mount...but it appeared intact to me AND to a very experienced Tech upon close inspection done at my request.
Later, I decided that this was probably a manifestation of the engine "creep" that I have seen on several Vipers where the right side gradually rides UP on the motor mount (closing the original gap just a little) and the left side goes lower. "Viper Wizard" has addressed this "creep" in several posts concerning header installation questions where guys complain that with the new headers, the right sided pipe is too close to the upper side of the sidesill, and the left pipe seems about 2 inches too low. Wizard correctly advises "re-cradling" the engine in the mounts. This certainly has worked on a friends headers.
The next time that I change the oil on the 96 RT/10, I'll recheck it for the engine "creep"...and, by the way, Chuck (Viper Wizard) tells me that this is due to DECELERATION torque forces.
Finally, you are correct about some improperly done 998 recalls BLOCKING access to the oil filter on some Vipers...this is very obvious, especially on the full blown Gen II's where the filter normally can be dropped nearly straight down...the problem was due to an admitted mislabeling of the recall brackets at the source, coupled with a less than experienced installer following the errant labels without applying a common sense visual crosscheck (at least in MY opinion...with my "retrospectoscope") of the oil filter's future accessibility.
The key to determining the correct placement of the triangular braces after the recall lies in whether your VIEW of the filter is blocked when you stand directly under the filter and look up...Hope this is at least a minor help...others may add better info or insights.