To be able to is the form I would use as a speaker of Midwestern American. I know there are dialects that leave off the last particle, (NOT preposition, for those of you who have ending prepositions as your pet peeve), but the to should be accepted.
"To be able" sounds really awkward.
i think a simple way to say this would be:
If I tried, I could. or If I would try I could
Can this be an acceptable translation? To me it sounds like more natural English.