you will be fine. We have a tandem at the rugby club and have done 2 x 150 mile plus rides with 2 amateur rugby players (ie not athletes) on it with 26 x 1 3/8 front and back, both 36h.
just build it up with plain gauge spokes if you are worried. braking is the major concern. We retrofitted some deeeep dual pivot calipers which helps but a drum brake would be a worthy addition
you will be fine. We have a tandem at the rugby club and have done 2 x 150 mile plus rides with 2 amateur rugby players (ie not athletes) on it with 26 x 1 3/8 front and back, both 36h.
just build it up with plain gauge spokes if you are worried. braking is the major concern. We retrofitted some deeeep dual pivot calipers which helps but a drum brake would be a worthy addition