RE: Welcome to Club SAITO !
Depending on the age and service on the motor I found some rules to follow. Even with a brand new motor I at least pull the covers to check valve lash. Frequently I close that up to just above .001" anyway. Once the motor has a few hours break in it's time to recheck as this is normally the highest wear time in service. After that every few months is fine for me. I average 100 flights per season on the "Bolt.
You are limited to how high you will be able to lift the tank and keep some form of insulation. If the tank contact the airframe you can get fuel foaming and create another problem while trying to solve this one. From what I can see in the pics it appears you are using a thin walled tube. If clamping is not successful look at replacing the vent line with a good quality thick wall tubing.
Can you lower the motor mount centerline and retain ground clearance?
Although the angle is a bit extreme, the exhaust orientation should not cause any direct issues other than at the end of a run any remaining oil will drain back to the motor.
p.s. I also found silicone tubing can come with different amounts of flexibility. That thin wall option I brought up earlier came out to haunt me a while ago. When resurrecting a Seamaster after a 20+ year hiatus I found one little quirk that took months to find. Anything over 1/2 throttle had the motor starve for fuel. I cleaned the carb and every fuel system component exterior to the tank several times and in the most extreme I finally pulled the Fox 50BB and swapped in an OS 55AX. Nice engine and gads of power, but the problem remained. I finally traced it to that flexible tubing. During the rebuild I had installed that on the tank clunk line and found the vent line pressure at anything over half throttle caused it to collapse. Replaced that line with less flexible thick walled line and it is now a rocket.