Dumb question re: processing 4x5

I'm sorry if this has been answered before.  This is a legit question so 
please bear with me.

My set up is not optimum.  I do not have a dedicated darkroom (for now at 
least).  I've done many many rolls of film over the years.  I throw 
everyting into a changing bag, load up a reel and no problem.

I'm getting ready to process 4x5 sheet film for the first time.  It
requires 
a bit more space to handle the sheet film than rolls.  Since I do not have
a 
dedicated darkroom, I can't fill the tanks with the necessary chemicals, 
leave them on a tabletop, and just lift the film holder from tank to tank
in 
the dark.

So my question(s) is/are simple:  I've heard that because the processing 
tanks for 4x5 film take so long to fill, uneven development could result. 
Is this a real problem, or is it the opinion of someone really obsessive? 
Would I be better off making a light tight space to do this?

Advice welcome from all.

Thanks.