Want to higher a design to put a seat and adjust tilt table on the rear cargo area of the tricycle.

Need design to commission fabrication of mount for set and table

This here is a minibike frame in cad I'd like to make but I'm scared it won't be strong enough.

it's square tube mild steel 35mm 2mm / 1.4 inch and 1/6 thick. You guys thing it will be strong enough?

Edit: made some changes in cad, pictures can be found here and there in the comments