that are your options in resolve! in resolve 10 there are a lot of things very nle-similiar, finsihing-wise. of course, you have to deal with the limitaions of your machine, gpu, cpu, hdds etc.
but if it is not that kind of realtime 4k powerhorse, just render small parts and check the sync in realtime-hd. there is still the render-cache, and all the options mentioned before.
it might be inconvient, but think of it: you have very high expectations! finsihing in 4k with limited hardware – hell it is possible! and yes, you might have to make some compromises workflow/realtime-wise…
and smoke won’t change your hardware-limits either. if it is a red project, render it in 4k-dpx and make yourself some hd-proxies to stay realtime and check everything. then render 4k.