I'm definitely in the amateur category when it comes to aerodynamics, but here is my judgement on the matter:
1.  I certainly wouldn't take off with a full load in one tank and the other empty as the learning experience right after liftoff might be more that you'd like.
2.  I would be nervous about taking off knowing that there was only one fuel source, but then many airplanes only have one, so....
3.  The real problem, I think, is during landing.  The out-of-trim condition changes rapidly as the airspeed declines, requiring quite a bit of aileron input.  Another rapid skill-building experience.  I've landed my ES with maybe 15 gallons difference and it was uncomfortable.
4.  The second real problem is that the stall characteristics would certainly be dramatically changed for the worse.  The heavy wing is likely going to stall first and at the tip because of the aileron deflection, inducing a wing drop.  I would land fast and with flaps, as that reduces the angle of attack at the tip.

Is it safe?  Safety is a relative thing.

Quick comment on aileron trim tabs:  My ES had the trim tab hinge already installed so I left it.  But I thickened the trim tab to match the aileron trailing edge and I think it helps to reduce the amount of travel required.  I also tapered the sides and rounded the corners, eliminating torn shirts when bumping it.  I'd rather have an internal tab, but given that the hinge (and servo) was already there, I don't think I would go to the work to do it.

Gary Casey