Concur is compliance not booking software. All it does is assure that whatever the traveler is booking is within whatever policy the employer sets.

It sounds as though OP needs to consult his own corporate travel department or, if smaller, engage a corporate TA which suits his needs. What he proposes is not particularly hard or burdensome and can be handled quite easily by the larger TA's. But, a smaller one may suit his needs just as well.

The key to look at is how well the corporate TA integreates with the employer's own accounting software. It sounds as though these are projects and those might be billed to a client, thus making internal compatability essential.