If you go with a hub style house build a simple fold up plywood floor with some outdoor carpet on it. Always be safe, slick wet ice and a 6 sq ft hole in the ice are not a good mix.
If you have a portable fish house currently and it lets too much light in you can build a cover out of quilted moving blankets quick and cheep. Or just simply throw some blankets over the top of it. Once again build a small floor for it.
I have a very light hard side house (built by a cat fishing, turkey hunting, darkhouse spearing , FMer) and several portables also.
I really like the hard side and wouldn’t get rid of it but would not get rid of my 8 X 8 double canvas craft portable either.
Having tried many different types of darkhouses, the only thing I can agree on is that the perfect spear house is the one where the spear hole already cut in the ice.

If you want to try some out before buying just let me know. I have a multiple darkhouses set up all winter and you can try one of mine out for free anytime you would like.