I hit level 51 on my Tactical Officer without levelling up at all. I did spend a few skill points, but not enough to actually get to Lieutenant, and definitely not enough to get any special abilities, such as Evasive Maneuvers.
It was a lot of diplomatic missions, ground missions, Ker'rat, DSEs, and a few higher level missions when I had a friend to help me with all the space combat.
After about level 30 or so, space combat became extremely difficult if not impossible for me to solo. Even though I was using the Constitution class ship with the blue phasers that level with you, the lack of weapon slots, ensign only BO abilities, and Mark II shields, engines, deflectors, and consoles all made it too difficult.
On the other hand, for ground combat, Mark II personal shields didn't really hurt too much, when I had the ground weapons from the Featured Series that level with you.
So here's my question...has anyone else done this, or am I the first?
(When I started this whole endeavour, level 45 was still the level cap at the time...)