I've searched for and read quite a few discussions of using a strapless strap on like feeldoe by a man (held in anus) on a woman.

I am a beginner and wanted some assistance in trying this out.

The biggest issues raised are:

1) The bulb on the feeldoe (even the slim) may be too big for beginners.
2) The strapless strap on can become difficult to keep in place.
3) The strapless strap on is not long enough to reach all the way.

My questions therefore are:

1) what strapless strap on would suit this purpose best?
2) what strapless strap on has a smaller bulb or easier to insert bulb?
3) what harnesses would be suitable to be used in this situation?
4) what strapless strap on would be long enough for this purpose but still thin for a beginner?

Thanks in advance!!!