Bit different here in remotest North-West Ontario (Class B only starts at 16000'). Europe was a nightmare - Northern Holland has Class A down to 1500'.
Tend to fly here at 5000-10000' as 90-95% of our days are OK for VFR. When using the J3 (on straight floats) stick to a max 5000' - no mixture control so it runs overly rich above that.
Apart from the safety factors, the additional altitude makes XC Nav Ded Reckoning far easier.
Happy flying!