There is a risk in a 'flip' maneuver for a High C vessel This is dependent on three factors.
Firstly the final 'cruising' velocity of the ship. At a significantly high % of the speed of light even impacts with small particles, smaller even than a grain of sand can cause significant, perhaps catastrophic damage to a ship due to the kinetic energy accumulated by the vessel as it accelerates. At high enough speeds even gas molecules become problematic.
For this reason ships traveling at a high % of the speed of light would probably tend to try and minimize their horizontal cross-section (along their line of travel) i.e. be as long and 'thin' as possible rather than wide. This is a passive design measure as opposed to whatever 'active' (e.g. lasers?) countermeasures the designers decide to include.
So during a 'flip' maneuver the ship is potentially exposing its flank to incoming projectiles.
Second is the amount of time the ship needs to complete the flip (how powerful its attitude thrusters/gyroscopes etc are in proportion to its mass). Obviously the quicker the transition the less the danger.
Lastly its the density of potentially dangerous particles along your flight path. Which presumably can be calculated based on research and experience.
You end up with a risk calculation, your final velocity multiplied by the time it takes to flip and the probability of encountering dangerous particles during this process (minus a risk adjustment for any active countermeasures you can build in.)
So depending on how dangerous you decide to make the likelihood of impacts the designers might consider the extra mass and complication of a 'forward' facing drive nozzle to be worth the trouble. Its up to you.
(It might even be useful as defense measure e.g. the ship detects an incoming particle on a collision course and briefly fires up the front drive at low power to destroy/deflect the inbound object, assuming maneuvering or other options aren't available.)