Hi jawnn,
Your head still up in the air, yeap you opened a can of worms and you didn't even now it, but the fun part when its all said and done you will have a recumbent that is going to be so much fun to ride !!!
Now seriously, stop opening new threads, its easier for fellow members to keep track of your progress if you just keep posting and asking all your questions in one place that way everyone who helping you out can keep an eye on you......
I can't find the staton in engine. how much does it cost and does it have a cvt?
http://staton-inc.com/
link to main staton site
http://www.staton-inc.com/Results1.asp?Category=14&offset=0
link to various trike applications
Questions
does it have a cvt? NO staton builds his own gearbox's, pretty impressive lifetime guarantee.....(or you can buy the nuvinci hub extra)
I am thinking to use it backwards on my usx trike
the problem with this i don't think you would have clearance for the honda, maybe one of the two strokes Tanaka 49 or mits 43 but the noise would be VERY loud as your engine placement would be close to under the seat, clearance issues underneath would be of major concern.
Check out this pic once again
http://www.motoredbikes.com/attachment.php?attachmentid=12024&d=1224356200
I think keeping it behind is the best option for you, its going to be the least hassle for you to install, and their should be enough room for your storage.
drop dave a line at his workshop have a good chat with him, he will be able to clear up any doubts you have, and will be able to anwser any questions about alternative mounting ideas etc...
Its hard to make a commitment when you actually cant see this stuff first hand, but i will tell you this a vendor like staton produces A+ quality drives and you wont be disappointed.
good luck...