Sundance2018

Hi Everybody -
Am looking at beginning new scratch build project - Pace Spirit - and would appreciate some advice. Attached are a set of plans I have for this model and I would like other builders' views on wing joiner options / main spar options.
For a model of this size and type, I am used to having an aluminum or carbon fiber tube to join the wing halves together, but the plans in this case appear to show a short main beam spar of unknown composition likely spruce or composite carbon fiber).
I would appreciate your comments and expert building opinions.
Thx - Tom