Thanks guys for the replies and advice.
Ok. at least now i know that for wheelsets normal 36 spokes ones are ok for tandem off-road usage.
I guess the problem is trying to find the rear hub which has to be 145mm...
For now i think i will try out how the bike handles with the recon fork. If the handling/steering really suffers, the reason would be because it is too weak is it? ie flexes too much?
Would you guys have any recommendations for a suspension fork for my case? bearing in mind that my front wheel is QR. most single crown tough forks are all thru-axle!
Thanks!!