[tillacum]

So it’s a good idea to kind of trim the bottom branches too, from time to time?

[Tilted Irish Kilt]

tillacum:" So it’s a good idea to kind of trim the bottom branches too, from time to time?"

Yes ,.. but it depends on what you want to achieve with Rugosa Roses.
If you want impenetrable, take fresh spring root tips (green) and place in soil, later transplanted to fill in the base gaps.
Rugosa Roses are not known to suffer from black spot or powdery mildew as other 'cultured' roses are. They will even prosper in shaded areas under tree canopy .
Another option is to use "Rootone" , or "Bontone" (rooting powder)on summer or early fall green clippings.
Also , look for rooted plantlings invading adjoining areas for "freebies" because they will want to spread out.

[Tilted Irish Kilt]

tillacum:" So it’s a good idea to kind of trim the bottom branches too, from time to time?"

The only time I would cull out the bottom branches would be to remove sick and dead canes, as they steal vitality form the remainder of the plant.
Do so carefully with leather gloves and a 'long reach' anvil pruner.
Those thornes will draw blood in a heatbeat; I know from expierience.