One option are the Golden Motor kits, which can be mounted either front or rear and come as a throttle only with the option to add pedal assist. They offer higher power motors which are great for the hills or hauling a lot of weight. If you will consider pedal assist, then the Bafang BBS-02 systems are great mid drive options. All of these will preserve the rear internal gear system. If you're in the Central Texas area, contact Mike, the owner of Easy Street Recumbents for help.
That's not really recumbent, that's a crank forward (CF) design. Kind of half way between a regular bike and a recumbent. I have one and love it, very comfortable but easier to ride than a real laid back 'bent'.
I love the Falco hub motor in the rear of my recumbent trike.
I have a Rans CF and the front end is very light with all the weight on the rear wheel basically. If I was going to assist it, I'd go with a front wheel hub motor unless you want a mid drive. Weighting the front end a bit is barely noticed.