I think the real difficulty with basal level is that it's not an exact science. I believe most people's basal subsidises their bolus or vice versa to some extent. I've used Insuman basal which subsidised bolus considerably - it was fine as long as you pulled back on your bolus ratio for the meals where the basal was at peak; I've used Levemir which kept running out so I had to subsidise it with my bolus, increasing the dose to cover the fact the basal wasn't meeting my needs; now Tresiba which doesn't seem to subsidise or need subsidising so my bolus has gone to a different ratio again - however, it doesn't hold me completely stable - it has a very flat action, but I don't think my needs are really very flat!
In the end, basal does have an impact on the amount of bolus you need and vice versa - they are inseperably entwined. You just find the best balance for you. It's not perfect, but it's the best we've got to work with.
Smidge