Réf. : KR> KR Parts / engine mount

Yes, it is a fairly standard solution. I just did the same with mine (replaced some very large aluminum 50mm spacers with round 40mm diameter ones. Which made me discover that engine mounts are actually very thin walled steel tubing on my aircraft... Serge Vidal KR2 "Kilimanjaro Cloud" Canberra

Réf. : Re: KR> wing skins weight

I probably have the heaviest wings around! Mine are South-African made, by Peter Eich, and they are made of a thick fiberglass layer (no foam, except a few ribs). Only the leading edge is filled with expanded polystyrene foam. Mark Langford has proved that wing skins could be build very easily